To examine the effects of acute plasma volume expansion (APVE) on Vo2 kinetics, Vo2 peak and time to exhaustion during high-intensity cycle exercise, 8 healthy men completed step exercise tests from unloaded cycling to a work rate requiring ~ 85 % Vo2 peak with and without prior intravenous infusion of 7 mL.kg-1 of a commercial plasma volume expander. Pulmonary gas exchange was measured breath-by-breath and Vo2 kinetics were analysed using non-linear regression. APVE resulted in a significant reduction in [Hb] compared to the control condition (CON: 15.5 ± 0.8 vs. APVE: 14.7 ± 0.8 g.dL-1; P<0.05). The time constant describing the Phase II Vo2 kinetics was not significantly different between the conditions (CON: 33 ± 15 vs. APVE: 34 ± 12 s). However, APVE resulted in a higher end-exercise Vo2 (CON: 3.90 ± 0.56 vs. APVE: 4.12 ± 0.55 L.min-1; P<0.05) and a greater time to exhaustion (CON: 365 ± 58 vs. APVE: 424 ± 64 s, P<0.05). In conclusion, APVE has no effect on the Phase II Vo2 kinetics but leads to a higher Vo2 peak and extends time to exhaustion during high-intensity cycle exercise in moderately-trained subjects.