Copper basic halide compounds have been studied by thermogravimetric and differential thermal analyses. This study reveals the general pattern of thermal stability observed for cadmium and zinc basic halides.The initial mode of decomposition varied within the copper group. The iodides, bromides, and chlorides all decomposed via dehydroxylation and in this way resembled the Cd and Zn basic halides. The copper basic fluorides, on the other hand, decomposed by simultaneous dehydroxylation and dehydrofluorination which is in distinct contrast to the Cd and Zn basic fluorides.