We report the resistivity, structural, and magnetic susceptibility measurements for Tl0.5Pb0.5(Ca1−xMx)Sr2Cu2Oy superconductors with M equal to the natural mixture of rare-earth elements and x=0, 0.05, 0.1, 0.2, and 0.3, respectively. The powder x-ray diffraction profile indicates a single-phase, P4/mmm tetragonal crystal structure with a=0.380±0.002 nm and c=1.205±0.002 nm for a Tl0.5Pb0.5(Ca0.9M0.1)Sr2Cu2Oy superconductor. Tc (zero)’s were found to be 79, 91, 101, 97, and 87 K for x=0, 0.05, 0.1, 0.2, and 0.3, respectively. Hc1 of Tl0.5Pb0.5(Ca0.9M0.1)Sr2Cu2Oy was estimated to be around 1.8 kG at 5 K, and Jc about 1.35×103 A/cm2 with a 20 kG applied field at 5 K. The Meissner signal of this sample indicates the Tc onset ∼100 K, and the mass diamagnetic susceptibility −χg at 5 K is 2.52×10−3 cm3/g (field cooled at 100 G).