As-grown BiSrCaCuO thin films have been formed on MgO(100) substrates at various temperatures by RF magnetron sputtering from three targets in atmospheres of neat O2 and N2O/O2 mixtures (1:1). The three targets had slightly different compositions heavily doped with Pb: Bi3Pb3Sr2Ca2Cu3Ox, Bi2Pb2Sr3Ca3Cu3Ox and Bi2Pb2Sr2Ca2Cu4.5Ox. Both films formed in O2 and N2O/O2 mixtures at 660°C showed zero resistivity at 77–78 K. A film obtained at 540°C by N2O/O2 mixtures showed superconductivity, while a film obtained at the same substrate temperature by neat O2 did not. Gas mixtures of N2O and O2 used instead of neat O2 as a sputtering gas were effective in lowering the growth temperature by 20–40 degrees.