We have synthesized new superconductors of nearly single phase with zero‐resistance temperatures around 120 K employing a novel method for sintering. The samples included a nominal composition of (Tl0.64Pb0.2Bi0.16)Sr2Ca3Cu4Oz. This sample was prepared from the mixture of presynthesized (Tl0.64Pb0.2Bi0.16)Sr2CaCu2Oz(1212 phase), CaO, and CuO powders. The mixed powder was sintered at 920 °C in O2gas and post‐annealed at 400–600 °C in O2gas. The powder x‐ray diffraction revealed that the sample was isostructural with the Tl‐based (Tl, Pb, Bi)Sr2Ca2Cu3Oz(1223 phase). The sample exhibited a sharp superconducting transition atTonsetc=125 K andTR=0c=120 K and the superconducting diamagnetic signal at 10 K was about 20% of a full Meissner effect.