Solubility and hydrolysis of pyridoxine monooctanoates (PIN-MO) were studied. PIN-4MO was more soluble in organic solvents and water than PIN-5MO. In buffer solutions of a constant pH between 2 and 3,hydrolysis of PIN-MO obeyed an apparent first-order kinetics. The substance passing through the rat intestine was found to be PIN alone.