This　paper　investigates　steady　laminar　boundary　layer　flow　of　power　law　fluids　past　a　flat　surface　with　suction　or　injection　and　magnetic　effects.　A　new　nonlinear　diffusion　model　is　proposed,　which　takes　the　effects　of　power　law　viscosity　on　concentration　fields　into　account　by　assuming　that　the　concentration　field　is　similar　to　the　velocity,　with　a　modified　Fick＇s　law　of　diffusion　for　power　law　fluids.　The　governing　strongly　nonlinear　partial　differential　equations　are　reduced　into　a　set　of　coupled　ordinary　differential　equations　and　then　solved　numerically　by　the　shooting　technique　coupled　with　the　Runge-Kutta　scheme　and　the　Newton＇s　method.　The　effects　of　the　Hartmann　number,　the　suction　or　injection　parameter,　the　power　law　index,　the　concentration　power　law　index,　the　concentration　radio　parameter　and　the　generalized　Schmidt　number　on　the　velocity　and　the　concentration　fields　are　presented　graphically　and　analyzed　in　detail.　(C)　2015　Elsevier　Ltd.　All　rights　reserved.