WIFICAM will be able to monitor the known X-ray sources (Cyg X-1, Crab, Sco X-1). Also new X-ray sources will be discovered (about 20 X-ray transients every year) and localized to about 1'. In some cases, the rapid follow-up observations will immediately identify the optical counterpart. The expected sensitivity is 1 mCrab (5-sigma) for a 10E5 s integration time.