This paper presents a study of a hydromagnetic free convection flow of an electrically conducting micropolar fluid past a vertical plate through a porous medium with a heat source, taking into account the homogeneous chemical reaction of first order. A uniform magnetic field has also been considered in the study which acts perpendicular to the porous surface of the above plate. The analysis has been done by assuming varying permeability of the medium and the Rosseland approximation has been used to describe the radiative heat flux in the energy equation. Numerical results are presented graphically in the form of velocity, micro- rotation, concentration and temperature profiles, the skin-friction coefficient, the couple stress coefficient, the rate of heat and mass transfers at the wall for different material parameters. The study clearly demonstrates how a chemical reaction influences the above parameters under given conditions

Abd-ElAziz M. (2006): Thermal radiation effects on magnetohydro-dynamicmixed convection flow of a micropolarfluid past a continuously moving semi-infinite plate for high temperature differences. - Acta Mechanica, vol.187, pp.113-127.

Ariman T., Turk M.A. and Sylvester N.D. (1973): Microcontinuum fluid mechanics - a review. - Int. J. Engng. Sci., vol.11, pp.905-930.

Baehr H.D. and Stephan K. (1998): Heat and Mass Transfer. - Berlin Heidelberg: Springer-Verlag.

Chaudhary R.C. and Jain P. (2007): Combined heat and mass transfer in magneto-micropolar fluid flow from radiativesurface with variable permeability. - ZAMM, vol.87, pp.(8-9), 549-563.

Chaudhary R.C. and Sharma B.K. (2006): Combined heat and mass transfer by laminar mixed convection flow from avertical surface with induced magnetic field. - Journal of Applied Physics, vol.99, pp.34901-10.

Cussler E.L. (1998): Diffusion Mass Transfer in Fluid Systems. - 2nd ed. Cambridge University Press.

Das U.N., Deka R.K. and Soundalgekar V.M. (1994): Effects of mass transfer on flow past an impulsively startedinfinite vertical plate with constant heat flux and chemical reaction. - Forschung im Engenieurwesen Engineering Research Co., pp.284-287.

El-Amin M.F. (2001): Magnetohydrodynamic free convection and mass transfer flow in micropolar fluid with constantsuction. - J. Magn. Mater., vol.234, pp.567-574.

Elbashbeshy E.M.A. and Bazid M.A.A. (2000): Effect of radiation on forced convection flow of a micropolar fluid overa horizontal plate. - Can. J. Phys./Rev. Can. Phys., vol.78 (10), pp.907-913.

El-Hakiem M.A., Mohammadein A.A., El-Kabeir S.M.M. and Gorla R.S.R. (1999): Joule heating effects onmagnetohydrodynamic free convection flow of a micropolar fluid. - Int. Comm. Heat Mass Tran., vol.26(2), pp.219-227.

Eringen A.C. (1964): Simple microfluids. - Int. J. Engng. Sci., vol.2, pp.205-217.

Eringen A.C. (1966): Theory of micropolar fluids. - J. Math. Mech., vol.16, pp.1-18.

Eringen A.C. (1972): Theory of termomicrofluids. - J. Math. Anal. Appl., vol.38, pp.480-496.

Gorla R.S.R. (1992): Mixed convection in a micropolar fluid from a vertical surface with uniform heat flux. - Int. J. Engng. Sci., vol.30, pp.349-358.

Gorla R.S.R., Mohammedan A., Mansour M. and Hussein I. (1995): Unsteady natural convection from a heatedvertical plate in micropolar fluid. - Numerical Heat Transfer, Part A, vol.28, pp.253-262.

Gorla R.S.R., Slaouti A.S. and Takhar H.S. (1998): Free convection in micropolar fluids over a uniformly heatedvertical plate. - Int. J. Heat and Fluid Flow., vol.8, pp.504-518.

Helmy K.A. (1998): MHD unsteady free convection flow past a vertical porous plate. - ZAMM, vol.98, pp.255-270.

Helmy K.A., Idriss H.F. and Kassem S.E. (2002): MHD free convection flow of a micropolar fluid past a verticalporous plate. - Can. J. Phys./Rev. Can. Phys., vol.80 (12), pp.1661-1673.

Hiremath P.S. and Patil P.M. (1993): Free convection effects on oscillatory flow of couple stress field through a porousmedium. - Acta Mech., vol.98, pp.143-158.

Ibrahim F.S., Hassanien I.A. and Bakr A.A. (2004): Unsteady magneto-hydrodynamic micropolar fluid flow and heattransfer over a vertical porous plate through a porous medium in the presence of thermal and mass diffusion with aconstant heat source. - Can. J. Phys./Rev. Can. Phys., vol.82 (10), pp.775-790.

Kandasamy R., Periasamy K. and Prashu Sivagnana K.K. (2005): Effects of chemical reaction, heat and mass transferalong wedge with heat source and concentration in the presence of suction or injection. - Int. J. Heat Mass Transfer, vol.48, pp.1388-1394.

Kim Y.J. (2001): Unsteady convection flow of micropolar fluids past a vertical plate embedded in a porous medium. - Acta. Mech., vol.148, pp.105-116.

Kim Y.J. (2004): Heat and mass transfer in MHD micropolar flow over a vertical moving plate in a porous medium. - Trans. Porous Media, vol.56, pp.17-37.

Kim Y.J. and Fedorov A.G. (2003): Transient mixed radiative convection flow of a micropolar fluid past a movingsemi-infinite vertical porous plate. - Int. J. Heat Mass Transfer, vol.46 (10), pp.1751-1758.

Kim Y.J. and Lee J.C. (2003): Analytical studies on MHD oscillatory flow of a micropolar fluid over a vertical porousplate. - Surface and Coatings Technology, vol.171, pp.187-193.

Lukaszewicz G. (1999): Micropolar Fluids. - Theory and Applications, Boston: Birkhaüser.

Muthucumarswamy R. (2002): Effects of a chemical reaction on moving isothermal vertical surface with suction. - Acta. Mech., vol.155, pp.65-70.

Muthucumarswamy R. and Ganesan P. (2001): First order chemical reaction on flow past an impulsively startedvertical plate with uniform heat and mass flux. - Acta. Mech., vol.147, pp.45-57.

Perdikis C. and Raptis A. (1996): Heat transfer of a micropolar fluid by the presence of radiation. - Heat and Mass Transfer, vol.31 (6), pp.381-382.

Perdikis C. and Raptis E. (2006): Unsteady MHD flow in the presence of radiation. - Int. J. of Applied Mechanics and Engineering, vol.11 (2), pp.383-390.

Rahman M.M. and Sattar M.A. (2006): Magneto-hydrodynamic convective flow of a micropolar fluid past acontinuously moving vertical porous plate in the presence of heat generation/absorption. - ASME J. Heat Transfer, vol.128 (2), pp.142-152.

Raptis A. (1998): Flow of a micropolar fluid past a continuously moving plate by the presence of radiation. - Int. J. Heat Mass Transfer, vol.41, pp.2865-2866.

Raptis A. and Massalas C.V. (1998): Magnetohydrodynamic flow past a plate by the presence of radiation. - Heat and Mass Transfer, vol.34, pp.107-109.

Raptis A. and Takhar H.S. (1999): Polar fluid through a porous medium. - Acta Mechanica, vol.135, pp.91-93.

Raptis A. Perdikis C. and Angew Z. (1998): Viscoelastic flow by the presence of radiation. - Math. Mech., vol.78 (4), pp.277-279.

Rees D.A.S. and Pop I. (1998): Free convection boundary layer flow of a micropolar fluid from a vertical flat plate. - IMAJ. Appl. Math., vol.61, pp.179-197.

Sharma B.K. and Chaudhary R.C. (2008): Hydromagnetic unsteady mixed convection and mass transfer flow past avertical porous plate immersed in a porous medium with hall effect. - Engineering Transactions, vol.56(1), pp.3-23.

Sharma B.K., Agarwal M. and Chaudhary R.C. (2006): MHD fluctuating free convective flow with radiation embeddedin porous medium having variable permeability and heat source/sink. - Journal of Technical Physics, vol.47(1), pp.47-58.

Sharma B.K., Chaudhary R.C. and Agarwal M. (2007): Radiation effect on temperature distribution in threedimensionalCouette flow with injection or suction. - Applied Mathematics and Mechanics, vol.28(3), pp.309-316.

Sharma B.K., Chaudhary R.C. and Agarwal M. (2008): Radiation effect on steady free convective flow along a uniformmoving porous vertical plate in presence of heat source/sink and transverse magnetic Field. - Bull. Cal. Math. Soc., vol.100, pp.529-538.

Sharma B.K., Chaudhary R.C. and Sharma P.K.(2007): Fluctuating mass transfer on three-dimensional flow through aporous medium with variable permeability. - Advances in Theoretical and Applied Mathematics., vol.2(3), pp.257-267.

Sharma B.K., Jha A.K. and Chaudhary R.C. (2006): Radiation effect with simultaneous thermal and mass diffusion inMHD mixed convection flow from a vertical surface with ohmic heating. - Romania Journal of Physics, vol.51(7-8), pp.715-727.

Soundalgekar V.M. and Takhar H.S. (1983): Flow of micropolar fluid past a continuouslymoving plate. - Int. J. Eng. Sci., vol.21, pp.961-965.

Takhar H.S. and Soundalgekar V.M. (1980): Heat transfer in a flat plate flow of a micropolar fluid. - Rheologica Acta, vol.19, pp.525-526.

Takhar H.S. and Soundalgekar V.M. (1985): Flow and heat transfer of micropolar fluid past a porous plate. - Indian J. Pure Appl. Math., vol.16, pp.552-558.

Takhar H.S. and Soundalgekar V.M. (1985): Flow and heat transfer of a micropolar fluid past a continuously movingporous plate. - Int. J. Eng. Sci., vol.23, pp.201-205.

Yucel A. (1989): Mixed convection in micropolar flow over a horizontal plate with surface mass transfer. - Int. J. Eng. Sci., vol.27, pp.1593-1602.