Under the optimum conditions worked out for the condensation of urea, aromatic aldehydes and ammonium acetate, the reaction has been extended to thiourea. 2-Thioketo-4, 6-diaryl hexahydro-s-triazines have been obtained in all the cases in better yields; 1, 3-bis-arylidene thioureas could be isolated only in a few cases. The ultraviolet and infrared absorption data for some of the thioketo-hexahydro-s-triazines are recorded and the >C = S stretching frequency in these compounds has been assigned.