We previously showed that NADPH oxidases (Nox) especially Nox2 mediate systemic and cellular responses to intermittent hypoxia (IH). However, the mechanisms by which IH activates Nox2 have not been examined. We recently reported that xanthine oxidase (XO) activation by IH generates ROS which leads to increased intracellular calcium. Given that calcium activated PKC is required for Nox2 activation, we tested the hypothesis that XO activation mediates IH increased Nox activity via ROS augmented calcium. Allopurinol, a XO inhibitor or silencing of XO in PC12 cells prevented IH‐induced Nox2 activation by inhibiting Nox2 complex formation at the membrane. Treatment of cells with Xanthine/XO under normoxia mimicked the effects of IH. Our results further demonstrate that ROS generated by XO, contribute to IH induced Nox activation by increasing intracellular calcium levels. IH augmented PKC activity by phosphorylation of alpha subunit which was inhibited by allopurinol and BAPTA (calcium chleator). More importantly, inhibition of PKC activity by allopurinol abolished Nox2 complex formation. These results demonstrate that ROS generated by XO activates PKC alpha via calcium resulting in IH augmented Nox activity. Supported HL‐ ‐90554.Grant Funding Source: HL‐90554