The effect of a new Cl-2 gas-based activation for CdTe/CdS thin him solar cells has been examined. Devices deposited by close space sublimation were treated using this method and compared with otherwise identical control devices activated using a conventional CdCl2 treatment. Depth-dependent carrier collection functions were obtained by measuring the current induced under electron beams of varying energy; this data was deconvoluted using carrier generation functions modelled using Monte Carlo simulations. The resultant measurements show that the performance of the chlorine treated device falls within the range of values measured for CdCl2 treated cells.