Thymolphthalein monophosphate disodium hydrate serves as a chromogenic substrate for the detection of acid phosphatase and alkaline phosphatase. During the enzymatic reaction, thymolphthalein is liberated which elevates the medium's pH, facilitating easy detection through color production and halts hydrolysis. Additionally, this compound is utilized for the specific identification of prostatic phosphatase in serum [1] [2].