Diamond-like carbon (DLC) films were synthesized by a combined PVD and PECVD process to produce a multilayered structure consisting of a Ti interlayer, a graded transition layer, and the carbon film. The oxidation behavior of DLC films was investigated using thermogravimetric (TGA) and differential thermal analyses (DTA). The phase identification and microstructural examinations were conducted by XRD, Raman, and SEM/EDS. According to those results, DLC films disintegrated at 350°C, showing typical graphitic transformation and oxidation behavior. The weight loss as a result of oxidation of carbon followed a linear reaction rate of −2.3×10 −4 g/mincm 2 . At 450°C, oxidation of the underlying TiN/TiC x N y interlayer occurred in addition to the oxidation of DLC. Weight gain caused by the formation of TiO 2 was observed. The overall oxidation kinetics of DLC is close to a parabolic behavior with k p =5.48×10 −5 mg 2 /cm 4 h. Surface cracking of the film resulted from stress relief. The microhardness of DLC films decreased with increasing annealing temperature due to the graphitization and oxidation of DLC. The transition temperature was confirmed using the results from the Raman analysis.