An Arlington Circuit Court jury acquitted a Southeast Washington man last night of 16 charges ranging from robbery to sodomy and attempted rape in connection with a holdup at a fast-food restaurant in which two women were sexually assaulted.

Dallas D. Hammond Jr., 31, had admitted taking part in several similar robberies in which employes were forced back into restaurants after closing hours and locked in walk-in refrigerators. But he denied participating in the September 1981 holdup at a McDonald's restaurant in Arlington for which he was on trial.

Hammond has already been sentenced to life imprisonment plus 65 years for robberies of McDonald's and Gino's restaurants in Montgomery, Prince George's and Charles counties. He is facing robbery charges in Alexandria.

The Arlington jury first reported it was deadlocked, but was told by Circuit Judge Paul D. Brown to continue deliberating and 2 1/2 hours later, at 6 p.m., returned with its verdict. One juror said the panel had not been persuaded there was enough evidence to prove that Hammond was one of the three men who held up the restaurant.

One of two male restaurant employes and Linval Barret, accused of driving Hammond's getaway car, had identified Hammond in court as the man who produced a gun and took the female employes out of the restaurant's walk-in refrigerator one at a time and sexually abused them. Three other victims could not identify him.

Defense attorney Liam O'Grady maintained that Barrett, who pleaded guilty to armed robbery charges, identified Hammond in an effort to get a more lenient sentence.

Barrett has not yet been sentenced. Another defendant in the case, Alfonso Burwick, is to be tried in May.