This article deals with an experimental study of pool boiling of acetone/water and propane/isobutane zeotropic mixtures. Water and acetone form non-ideal mixtures characterized by a very wide phase equilibrium diagram. Propane and isobutane, which are alkanes with very close thermophysical properties, form nearly ideal mixtures. The whole nucleate pool boiling curves of these mixtures have been performed for decreasing heat fluxes. The experimental heat transfer coefficients have been compared to the literature models. A reference heat transfer coefficient that is different from the usual ideal heat transfer coefficient is proposed to determine the heat transfer coefficient of mixtures for the whole nucleate pool boiling curve. That is not the case of the ideal heat transfer coefficient, which cannot be calculated for heat fluxes higher than the lower critical heat flux of the two components.