Radiation and chemical reaction effects on the steady boundary layer flow of MHD Williamson fluid through porous medium toward a horizontal linearly stretching sheet in the presence of nanoparticles are investigated numerically. Adequate similarity transformations are used to derive a set of nonlinear ordinary differential equations governing the flow. The resultant nondimensionalized boundary value problem is solved numerically by Runge–Kutta–Fehlberg fourth–fifth order method with Shooting technique. The profiles for velocity, temperature and concentration, which are controlled by a number of thermo-physical parameters, are presented graphically. Based on these plots the conclusions are given, and the obtained results are tested for their accuracy.