The effects of temperature-dependent viscosity on the heat and mass transfer in nonlinear MHD boundary layer flow past a vertical porous plate are studied in the presence of a magnetic field, thermal radiation, thermophoresis, and an nth-order homogeneous chemical reaction. The fluid properties are assumed to be constant except for the density variation with the temperature. The governing equations are converted in to a system of nonlinear ordinary differential equations which is solved numerically using the Nachtsheim and Swigert shooting iteration technique together with a sixth-order R-K integration algorithm. The dimensionless velocity, temperature and concentration profiles are shown graphically. The effects of dimensionless numbers and pertinent parameters on the skin friction, Nusselt number and Sherwood number are examined in the presence of a magnetic field and thermal radiation. It is found that skin friction is lower and Nusselt number is higher when the viscosity is temperature dependent. (C) 2015 Elsevier Ltd. All rights reserved.