The aqueous solubility of the macrocyclic aminal 1,3,6,8-tetraazatricyclo[4.4.1.1(3,8)]dodecane (TATD) at temperatures from 275 K to 303 K has been determined. The data of aqueous solubility of TATD and its variation with temperature have not been reported before. This compound has only been reported as "very soluble in water" at room temperature, soluble in chloroform, and slightly soluble in ether. The temperature dependence of TATD solubility in water is described by the van't Hoff plot and the modified Apelblat equation.