The aim of this study was to investigate the acute effect of ATP supplementation on performance and physiological responses during resistance exercise in recreationally resistance trained males. Eleven men (age= 27.5±5.5 yrs, weight= 83.4±9.8 kg, height= 182±0.04 cm) completed two randomized, double-blind trials: ATP supplement condition (ATP=400mg) or a placebo condition. Thirty minutes after supplement consumption, subjects performed four sets of half-squats until momentary muscular failure at 80% of the 1RM with two minutes of recovery between sets. The total number of repetitions, blood pressure, heart rate, blood lactate, and oxygen consumption were evaluated. The total weight lifted were higher for the ATP condition compared to placebo (Placebo= 3995.7±1137.8, ATP= 4967.4±1497.9 Kg; p= 0.005). Heart rate was higher at set-4 for ATP compared to placebo (p<0.001) and oxygen consumption during exercise was greater for ATP (p=0.021). There were no differences between conditions for lactate and blood pressure. In summary, a single oral dose of ATP supplementation improved lower body resistance training performance and energy expenditure in recreational resistance trained males.