We report the effects of biaxial strain on the charge ordering temperature Tco of the mixed-valent manganite perovskite oxide Pr0.5Ca0.5MnO3. Thin films were grown on SrTiO3, which has a 1.3% larger in-plane lattice parameter. Other substrates were used for comparison. Transport measurements combined with data from electron microscopy show that Tco is considerably enhanced. At thicknesses of the order of 10nm, where the films are fully strained, Tco is above 320K, more than 70K above the bulk value of 250K, while around 50nm, where relaxation has set in, the enhancement is around 40K. The bulk value is only reached at a thickness of about 150nm.