Coral bleaching is well recognised to be driven by high water temperature and high irradiance, both independently and in concert with one another. Ocean acidification affects coral calcification and some other aspects of coral physiology, as demonstrated in many experimental studies. However, the effect of ocean acidification on coral bleaching remains uncertain, and concern exists that ocean acidification may act as an enhancer of coral bleaching. In this study, we investigated the effects of ocean acidification at two levels (444 and 882 µatm pCO2) crossed with two levels of light (300 and 650 µmol photons m-2 s-1) and two water temperatures (25ºC and 29ºC) on colonies of the lace coral, Pocillopora damicornis, from Kaneohe Bay, Oahu, Hawaii. Ocean acidification and light treatments were applied over an eight week experiment. The two levels of temperature were only applied in the final week, providing time for corals to respond to ocean acidification first in the absence of heat stress. Whilst increasing light and temperature caused declines in areal Symbiodinium densities in P. damicornis, increasing ocean acidification did not. However, ocean acidification, light and temperature had a significant interactive effect on photosynthesis per Symbiodinium cell. Ocean acidification by itself, and in interaction with temperature or light, had a significant impact on several respiration parameters. Ocean acidification in a realistic late twenty-first century scenario does not appear to cause coral bleaching in P. damicornis. However, the same level of ocean acidification may significantly affect the primary productivity of P. damicornis in a synergistic manner with irradiance and temperature.