Аннотация:The existence of three ternary phases SMSeO3Cl, SMSe2-O5Cl, and SmSe3O7Cl is shown on the quasibinary line SmOCl-SeO2. The phase barogram and the phase diagram are determined by total pressure measurements and DTA. respectively. SmSe3O7Cl melts peritectical at 340 +/- 10degreesC. SmSe5OCl melts peritectical at 560 +/- 10degreesC while SmSeO3Cl shows no thermal effects up to 900degreesC. The data of enthalpies and entropies of the phases are evaluated from the total pressure measurements (Data see ,,Inhaltsubersicht").