Abstract: An MOCVD precursor composition useful for MOCVD formation of a non-linear optically active metal borate thin film, comprising: (I) an organometallic source reagent for a metal reactively forming a non-linear optically active metal borate, and (II) an organoborate compound of the formula: B(OR).sub.3, wherein each R is independently selected from H, alkyl, aryl, alkaryl, arylalkyl, alkenyl, fluoroalkyl, fluoroaryl, fluoroaralkyl, fluoroalkaryl, trialkylsilyl, and C.sub.5 -C.sub.8 carbocylic groups, as the aforementioned borate source reagent. Such composition may be employed for forming a non-linear optically active metal borate thin film on a substrate, via depositing by CVD on said substrate a metal from the organometallic source reagent and a borate from the organoborate compound, to react the metal with the borate and yield the non-linear optically active metal borate on the substrate.