The in vitro effect of produced water released by oil and gas platforms was assessed by exposing cod sperm cells to realistic concentrations of this mixture (100, 200, 500 ppm). We investigated produced water impact on enzymes of the aerobic (citrate synthase) and glycolytic metabolism (lactate dehydrogenase), lipid catabolism (lipase), as well as an anti-oxidant enzyme (catalase). Fertilization rates, viability, respiration, ATP, and total motility duration were also evaluated. To explore correlations between these parameters, we have also tested the effect of conserving sperm for 24 h at 4 degrees C. After conservation, fertilization success was decreased but other parameters were not affected. Produced water did not result in a significant change in fertilization; a significant increase in sperm protein amounts and citrate synthase activity can be observed. No correlations are found between parameters showing that sperm viability and unchanged energy levels do not translate into equivalent fertilization capacity. To conclude, exposure of sperm to produced water resulted only in subtle effects on cells. These findings bring information on the effect of produced water on sperm itself rather than on spermatogenesis or testis development of an exposed fish.