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Because of their significant magnetocaloric properties, Ca and Pb-doped LaMnO3 can be employed in magnetic refrigeration systems. The partial substitution effect of Ca2+ by Pb2+ cations on the structural, magnetocaloric properties, and critical behavior of mixed valence perovskites La0.8Ca0.2−xPbxMnO3 (0 ≤ x ≤ 0.15), synthesized by the flash combustion route, was studied in this work. The presence of structural transformations of the prepared ceramics from an orthorhombic structure (Pbnm space group) for samples with x ≤ 0.05 to a rhombohedral system ( R 3 - c space group) for x ≥ 0.1 was detected by X-ray diffraction analysis, which is related to the A-site disorder. The field-cooled (FC) magnetization indicated a second-order ferromagnetic-paramagnetic transition for the investigated samples when the temperature was increased. Due to the change in the Mn3+/Mn4+ ratio, substituting Ca2+ with larger Pb2+ ions increases the Curie temperature (TC) by increasing Pb doping content from 90 K for x = 0 to 205 K for x = 0.15. The magnetization isotherms of all samples showing a second-order phase transition were studied, where an applied magnetic field of 5 T, the value of maximum magnetic entropy variation / Δ S M max / for the sample with x = 0.15 was estimated to be 2.73 Jkg−1 K−1. In addition, it has a significant relative cooling power of about 276 Jkg−1 under the same applied magnetic field strength. The critical behavior of the samples was investigated close to TC. The exponent values were identical to the mean-field method, indicating a large disorder of spin magnetic moments in the perovskite compounds. [ABSTRACT FROM AUTHOR]