This study assessed the effects of trichloroacetic acid (TCAA), a newly recognized non‐volatile product of chlorine disinfection, on the oxygen uptake of dragonfly nymphs. This study utilized a range of TCAA from 1 ‐ 1000 ppb for a 96 hour period using a flow‐through exposure system. The results indicated a dose‐dependent increase in oxygen utilization which achieve statistical significance from control values at 100 and 1000 ppb. While previously published efforts have emphasized possible public health effects of TCAA as a result of consumption of chlorinated drinking water, the present findings indicate that TCAA is capable of causing environmental physiological alterations in an aquatic model organism in a model flow‐through system at environmentally relevant concentrations.