In this investigation, the heat and mass transfer characteristics in boundary layer flow about a stretching sheet in a porous medium filled with TiO2 – water and Al2O3 – water-based nanofluids, in the presence of internal heat generation or absorption and viscous dissipation with variable suction or injection effects is numerically studied. The similarity transformations are used to transform the governing boundary layer equations for momentum, energy and species transfer into a set of non-linear ordinary differential equations which are solved numerically by Keller-box method. The obtained numerical results are validated against results computed by using MATLAB bvp4c routine, and excellent agreement is observed. The impact of various pertinent parameters on velocity, temperature and concentration as well as the friction factor coefficient, local heat and mass transfer rates are derived and discussed through graphs and tables for TiO2 and Al2O3 water-based nanofluids. The present study reveals that an increase in Eckert number (Ec) and heat generation/absorption parameter (Q) significantly decreases local heat transfer rate.