Sr1-xLaxCuO2-delta (x=0.10-0.20) thin films exhibiting an oxygen-deficient 2V2ap x 2V2ap x c structure ap and c represent the cell parameters of the perovskite subcell were epitaxially grown by means of pulsed laser deposition in low-pressure oxygen ambient. (001) KTaO3 and (001) SrTiO3 single crystals were used as substrates, with BaTiO3 as buffer layer. The Sr1-xLaxCuO2-delta films were oxidized during cooling down in order to yield the infinite-layer-type structure. By applying this method, high quality single-phase Sr1-xLaxCuO2 thin films could be obtained for 0.10<x<0.175 doping range. The films grown on BaTiO3 /KTaO3 show superconductivity for 0.15<x<0.175 with optimum doping at x=0.15, in contrast with previously reported data.