Magnetohydrodynamic entropy generation of two immiscible fluids inside an inclined channel in the presence of different types of nanoparticles is examined. Channel consists of two regions, one Newtonian clear fluid and another Newtonian nanofluid with water as the base fluid and different nanoparticles including copper (Cu), copper oxide (CuO), aluminum oxide (Al2O3) and titanium dioxide (TiO2). Governing equations are solved with homotopy analysis method to highlight the effect of magnetic parameter, Grashof number, inclination angle and solid volume fraction on the total entropy generation for all types of nanoparticles. Results demonstrate that increasing of Grashof number, inclination angle and solid volume fraction amplifies the total entropy generation, while the enlargement of magnetic parameter reduces it especially for solid volume fractions greater than 15%. Among the several case studies performed, it is seen that water-TiO2 nanofluid is the best nanofluid from the viewpoint of entropy generation minimization. It is also found that the maximum total entropy generation is 1.268 and takes place for water-Cu nanofluid. Moreover, it is observed that the entropy generation component due to heat conduction of water-Cu nanofluid occupies 33.62% of the maximum total entropy generation and consequently that is the main cause of irreversibility in this study.