Doping of Cu-poor CuInS2 thin films by sodium and oxygen species, such as O-2 and O, was investigated by SIMS and conductivity measurements. Increased oxygen concentration is found for Na-doping. The SIMS signals of CuO and CuOS were detected. They coincide for O-doped films but differ for Na and O-2 doped films. This is interpreted as due to grain boundary effects. Na doping lends to an increase in lateral conductivity. This finding supports the model previously proposed by [L. Kronik, D. Cahen, H.W. Schock, Adv. Mater. 10(1998)31] that oxygen plays a major role in Na doping. The presented results. furthermore, propose oxygen single doping for chalcopyrite films.