The precursors of La1-xPbxMnO3 manganite colossal magnetoresistive ceramics were prepared by co-precipitation process via the oxalate route using oxides as the starting materials. The mathematical model of the solution was developed and the conditions of the complete co-precipitation of all cations existing in the solution as insoluble oxalates were determined. La1-xPbxMnO3 manganites were synthesized by high-temperature thermal treatment of the precursors. It was demonstrated that the two-stage annealing procedure: 12 hours at 800 degreesC in air and 12 hours at 950 degreesC in flowing O-2 permits to synthesize compositions with the required stoichiometry exhibiting colossal magnetoresistive properties.