The thermal decomposition profile for the product of organometallic chemical vapor deposition (OMCVD) of tetra(tert-butoxy)zirconium on an oxide-modified aluminum surface depends on the initial surface hydroxyl group coverage. Controlled thermolysis of the tri(tert-butoxy)zirconium species bound to the low hydroxyl group content surface shows nearly complete degradation to ZrO2 at T > 350 K. In contrast, thermolysis of the tri(tert-butoxy)zirconium species bound to the hydroxyl group-saturated surface gives a thermally more stable (to >450 K) di(tert-butoxy)zirconium surface complex. Deposition and thermal evolution reactions were followed by both reflection-absorption infrared and X-ray photoelectron spectroscopies.