Oxygen consumption rates of adult spring chinook salmon Oncorhynchus tshawytscha increased with swim speed and, depending on temperature and fish mass, ranged from 609 mg O~2~ h^−1^ at 30 cm s^−1^ (c. 0·5 BL s^−1^) to 3347 mg O~2~ h^−1^ at 170 cm s^−1^ (c. 2·3 BL s^−1^). Corrected for fish mass, these values ranged from 122 to 670 mg O~2~ kg^−1^ h^−1^, and were similar to other Oncorhynchus species. At all temperatures (8, 12·5 and 17° C), maximum oxygen consumption values levelled off and slightly declined with increasing swim speed >170 cm s^−1^, and a third‐order polynomial regression model fitted the data best. The upper critical swim speed (U~crit~) of fish tested at two laboratories averaged 155 cm s^−1^ (2·1 BL s^−1^), but U~crit~ of fish tested at the Pacific Northwest National Laboratory were significantly higher (mean 165 cm s^−1^) than those from fish tested at the Columbia River Research Laboratory (mean 140 cm s^−1^). Swim trials using fish that had electromyogram (EMG) transmitters implanted in them suggested that at a swim speed of c. 135 cm s^−1^, red muscle EMG pulse rates slowed and white muscle EMG pulse rates increased. Although there was significant variation between individual fish, this swim speed was c. 80% of the U~crit~ for the fish used in the EMG trials (mean U~crit~ 168·2 cm s^−1^). Bioenergetic modelling of the upstream migration of adult chinook salmon should consider incorporating an anaerobic fraction of the energy budget when swim speeds are ≥80% of the U~crit~.