A D.C. police officer was convicted yesterday of punching two people he had arrested.

Officer John Hilderbrand, who will be sentenced in September, faces up to two years in prison for the two misdemeanor assault convictions. His attorney said he had not decided whether to appeal.

A D.C. Superior Court jury deliberated for nearly 2 1/2 hours at the close of the week-long trial. As the jury foreman read the verdict, Hilderbrand stared ahead expressionless, clasping his hands in front of him.

For the past year Hilderbrand, an eight-year member of the force, has been assigned to duties that do not involve face-to-face contact with the public. Police officals said yesterday that his future status would be determined by administrative review.

Prosecutors charged that in June 1988, Hilderbrand punched Royette Smith, now 25, several times in the face after their cars nearly collided at a Southeast Washington intersection. At the time, Hilderbrand was off duty, driving his personal car and wearing civilian clothes.

Smith testified that when she reached for her driver's license and registration, Hilderbrand tried to remove her keys from the ignition.

When she tried to prevent him from taking the keys, she said, he began hitting her in the face. Smith then rolled up her window to trap his arms, as both she and the officer called for assistance.

Smith was arrested when more officers arrived, but charges against her were soon dropped. She then filed a complaint against Hilderbrand before the Police Civilian Complaint Review Board, which found in her favor. She has also brought a civil lawsuit against the officer.

The second incident for which Hilderbrand was convicted involved his September 1988 arrest of Everett Richardson.

Richardson testified that Hilderbrand handcuffed him and pushed him face down into a police car. When he tried to sit upright, he said, Richardson accidentally kicked Hilderbrand in the chest. Hilderbrand then jumped on Richardson and began punching him in the back of the head.

Hilderbrand took the witness stand in his own behalf to dispute witness' accounts of the incidents. He admitted striking Smith and Richardson, but said he was acting in self-defense and was using the minimum force necessary to make an arrest.

The jury disagreed. One juror said yesterday the decision came down to "whether the admitted assaults were justified." He said the jury did not believe Richardson or Smith posed any physical threat to the heavyset Hilderbrand.

As he left the courtroom Hilderbrand said, "This is a travesty. I feel betrayed and singled out."