Two new heterocyclic Organmercury compounds were prepared from the reaction of Sulfamethaxazole and Sulfadiazine with 4-acetaminophenol as a coupler and separated as solids with characteristic colors. these compounds were characterized by F.T.IR-spectroscopy 1H-NMR , Micro-elemental Analysis and UV-Vis spectroscopic techniques . The work involves a study of acid – base properties compounds at different pH values, the ionization and protonation constants were calculated. The thermal behavior of these two compounds were investigated on the basis of thermogravimetric (TGA) and differential thermogravimetric (DTG) analyses, Thermal decomposition of these compounds is multi-stage processes.