This study focused on studying the chemical stabilization of arsenic (As) in mining tail from a contaminated site in the north of Mexico. The main objective was to evaluate the behavior of As solubility in the contaminated soil after its amendment with manganese oxide (cryptomelane) prepared by two different procedures (McKenzie and Gangas). The initial concentration of total As was 2797 mg kg−1 during 10 days of experimentation under controlled conditions; it was found that the reduction of soluble arsenic occurred since the second day using cryptomelane obtained by Gangas procedure.