A 31-year-old Washington lawyer yesterday was indicted on eight counts of engaging in sex acts with juveniles he had been appointed to represent in D.C. Superior Court cases.

Roger H. Moore, a member of the D.C. bar since 1974, allegedly committed sodomy and other sex offenses in his K Street law office and a Southeast Washington apartment with juveniles aged 14 to 17, according to a law enforcement source.

The 16-count indictment returned by a D.C. Superior Court grand jury charged Moore with 10 counts of sodomy, one count of assault with intent to commit sodomy, four counts of taking indecent liberties with a minor, and one count of assault.

The incidents involved eight different youths, according to the indictment, and took place from March 1, 1977, through Sept. 12, 1979.

Moore's attorney, R. Kenneth Mundy, said yesterday that Moore "is fully prepared to answer the charges" and will plead innocent.

Moore currently is free on bond pending an appeal of an Arlington County conviction last year on charges that he sexually fondled a 13-year-old boy whom he had been appointed to represent in juvenile court. Moore has been suspended from practicing law pending the outcome of that appeal, according to a law enforcement source.

Moore, a graduate of George Washington University Law School, could not be reached for comment.