[en] 4 new analogues of 4-(2-benzthiazolylazo)-resorcinol have been synthesized. These are: 4-(2-benzthiazolylazo)-2-nitroresorcinol, 4-(6-bromine-2-benzthiazolylazo)-2-nitroresorcinol, 5-(2-benzthiazolylazo)-2,4-dioxybenzoic acid and 5-(6-bromine-2-benzthiazolylazo)-2,4-dioxybenzoic acid and 5-(6-bromine-2-benzthiazolylazo)-2,4-dioxybenzoic acid. Acid ionization constants for these reagents have been determined spectrophotometrically in 50% ethanol at 0.1 ionic strength. Color reactions with metal ions have been studied and the pH region of complexing and the lambdasub(max) of colored complexes determined. Some of the synthesized reagents show promise for photometric determination of copper, mercury, zinc, cadmnum, vanadium and palladium