A feasible method for the synthesis of phosphinothioates from sulfinic acid derivatives and phosphine oxides is described. This reaction can be carried out in an open flask at room temperature and in an aqueous medium. The scope of the sulfinic acid derivatives is extensive, with a wide range of sulfinate esters, sulfinic acids, and sodium sulfinates compatible with these conditions, with good to excellent yields of phosphinothioates. In addition, a gram-scale synthesis with this reaction is achieved. A mechanism of this procedure was proposed.