Double exchange reactions occur between CA-HAp and lead ions, the latter replacing Ca²⁺ ions in the network. The reaction is specific since Ca-HAp in a strong basic environment is stable and Pb-HAp in acid. This study summarized calcium hydroxyapatite by microwave heating, after which it was introduced in solutions of Pb(NO₃)₂ with different concentrations between 0.01 and 0.1 mol. It was found that, depending on working conditions, can result in either solid solution (Ca,Pb)(PO₄)₃(OH)_0.67, hydrated phosphate lead or mixing two types of hydroxyapatite, Ca-HAp, respectively Pb-HAp. They defined the conditions under which hydroxyapatite calcium passes into hydroxyapatite lead.