This paper studies the Soret and Dufour effects on MHD flow of a Casson fluid past a stretching sheet in the presence of chemical reaction, viscous dissipation and variable thermal conductivity. The fluid is taken to be electrically conducting and the flow is induced by a stretching surface. The governing partial differential equations are transformed into non-linear ordinary differential equations using similarity transformations. The resulting equations are then solved numerically by shooting method. The impact of various stimulating parameters on the flow, heat and mass transfer characteristics are analysed and discussed in detail through graphs. It is observed that the thermal conductivity parameter has a lot of control on heat and mass transfer rates.The variable thermal conductivity also has an impact in enhancing the temperature hence fluids with less thermal conductivity (small values of ) may be opted for effective cooling. A comparison with previously published work is accomplished and the outcomes are found to be in excellent agreement.