Polyimides synthesized by vapor deposition have potential uses as gas barriers, dielectric coatings, and fusion laser targets. Efforts to further refine the process dictated an extensive understanding of the imidization of ODA-PMDA poly(amic acid) to ODA-PMDA polyimide. To aid in understanding this process, we have utilized MALDI-TOF MS to identify the products formed at various thermal intervals. The spectra obtained in this study identify critical temperatures of imidization (130-160 degreesC), average molecular mass growth, and previously unreported end group changes from a predominance of ODA in the uncured poly(amic acid) to a predominance of PMDA end groups in the fully cured polyimide. The gases evolved during curing were identified by GC/MS as monomer which was trapped in the solid poly(amic acid) during vapor deposition.