HOUSTON (AP) _ The 1985 Houston Open golf tournament lost more than $100,000, forcing operators of the PGA tour stop to dip into reserve money in order to meet charity commitments, officials said.

''The losses were a little greater than we expected, but considering the losses, I think our board showed optimism,'' Duke Butler, executive director of the Houston Golf Association, said Wednesday.

The financial loss was the first for the tournament since 1966-67, when it was rained out and had to be rescheduled.

Tournament officials had to scramble in their fund-raising efforts when Coca-Cola withdrew its sponsorship, worth $500,000. The break-even point for the tournament was about $1.5 million.

The tournament also incurred extra expenses because it moved to a new course at The Woodlands, Butler said.

He said the chances of finding another major commercial sponsor for next year's event were better than 50-50.

''We knew March 1 that we were going to take a loss,'' he said. ''But I don't think anyone who attended the tournament could tell one bit of difference.''

The four-day event in April, won by Raymond Floyd, drew a record 137,500 spectators.