Poly(N-vinylcarbazole) (PVK) powder has been doped by bromine at room temperature and also at 370, 420 and 470 K for 24-72 h. It is shown, by electron spin resonance (e.s.r.), optical absorption, X-ray photoelectron spectroscopy (XPS), that a charge transfer complex (CT complex) is formed between PV-K and Br. However, some bromine is found to react with PVK, even after doping at room temperature, by addition or substitution, since not only bromine anion, which evidences the presence of the charge transfer complex, but also neutral bromine, has been detected by CPS. After heating, our results show that PVK is transformed into a new, more insoluble polymer. This polymer is amorphous, while some traces of carbazole and NH4Br are present in the powders. The increase of the conductivity is probably related to the formation of some pi bonds in the new amorphous polymer.