This paper aims to study the problem of unsteady mixed convection in a stagnation flow on a heated vertical surface embedded in a nanofluid-saturated porous medium. The employed mathema tical model for the nanofluid takes into account the effects of Brownian motion and thermophoresis. The presence of a solid matrix, which exerts first and second resistance parameters, is considered in this study. The self-similar solutions for the system of equations governing the problem are obtained. The resulting system of ordinary differential equations that govern the flow is solved numerically using fourthfifth order Runge-Kutta with shooting method. Numerical results for the dimensionless velocity, temperature and nanoparticle volume fraction as well as skin friction, Nusselt number and Sherwood number are produced for different values of the influence parameters.