This Letter reports preliminary findings on the role of chloride poisoning during steam reforming of chlorocarbons over nickel catalysts. When conversions of chlorocarbon are very high and thermal pyrolysis absent, the principal effect of chloride is to decrease water-gas shift and CH4-steam reforming activity. Product carbon dioxide/carbon monoxide ratios are then far from equilibrium and methane remains unconverted when introduced into the feed. These results are linked to previously published surface science studies.