Low dielectric constant (low k) fluorocarbon films have been deposited by pulsed plasma chemical vapor deposit-ion with a variety of different precursors. Deposition rates and resulting film composition have been characterized as a function of pulse timing, deposition temperature, and substrate precursors. To examine the thermal decomposition process, we have constructed a novel appartus for observation of decomposition, utilizing laser interferometry to examine changes in film thickness/properties during the heating process. Using the technique in conjunction with X-ray photoelectron spectroscopy, we have identified at least two methods of decomposition. Loss of hort chain side groups is seen to occur at temperatures as low as similar to 100 degrees C. At higher temperatures, bulk film decomposition is observed, and the rate is limited by mass-transport of the decomposition products. Additionally, plasma-deposited films are observed to incorporate oxygen on atmospheric exposure. Oxygen groups formed in the film are believed to contribute to the decomposition process.