A new route, starting from nanoparticles of mixed ions, has been used to synthesize high-quality thin films of a complex perovskite (YBa2Cu3O7-delta, YBCO). Currently, the most promising approach for making YBCO films uses metal trifluoroacetates. In comparison, the present method using a colloidal dispersion of nanoparticles is seen to produce crystalline, well textured films at much faster heating rates and having much lower porosity. Whereas there is scope for further optimization, this effort has rapidly yielded superconducting films with transition temperature of 89.5 K and self-field critical current density up to 2.4 MA cm(-2) at 77 K.