Abstract: The in-situ monitoring of metalorganic precursor delivery in a metalorganic chemical vapor deposition oxide system in high temperature super conductors (HTSC) film growth is accomplished by utilizing the distinct absorbance bands for metalorganic compounds. As an ultraviolet-visible light beam is passed through an effluent metalorganic gas stream the relative change in ultraviolet-visible absorbance of the ultraviolet-visible light beam passing through the effluent metalorganic gas stream is monitored. Stoichiometry control is achieved by feeding back absorbance data to a controlling parameter such as carrier gas mass flow rate, thus stabilizing fluctuations in source concentration in the bubble effluent from a computer or similar monitoring device. Such an apparatus and method improves the stoichiometry control of mixed metal oxide film deposition and increases the manufacturability of thin films.