A solid state reaction method for the production of tetrabasic lead sulfate includes the steps of mixing a stoichiometric mixture of 3PbO.PbSO4.H2O and PbO and heating the stoichiometric mixture of 3PbO.PbSO4.H2O and PbO at a temperature between 500 and 700.degree. C. for 3 to 8 hours. The method also includes the steps of deagglomerating and sieving resulting tetrabasic lead sulfate.