England left-arm spinner Norman Gifford was 44 years old when he made his debut in a one-day tournament in Sharjah in 1985. Norman had been the assistant manager on a couple of overseas tours and took over as captain for this tournament when a few senior players were rested.
Next comes South African Clive Rice, who was 42 years old when he captained their first official one-day internationals, in India in November 1991. If you include the non-Test teams then the oldest debutant in one-day internationals and the oldest player overall too is the Barbados-born opener Nolan Clarke, who was 47 when he played for the Netherlands in the 1996 World Cup.
