Hydrolysis of chlorophyll a to yield chlorophyllide a was performed in the presence of papain in organic solvents containing ca. 10 % water at room temperature in the dark. The conversion yield was found to be highest in acetone followed by acetonitrile, methanol, ethanol and 2-propanol. The yield of hydrolysis for chlorophyll a → chlorophyllide a increased up to ca. 30 % with incubation temperature from 30 °C to 60 °C. The yield is high enough to prepare chlorophyllide a as a photosensitizer for photodynamic therapy