The walls were freshly painted cream white. Metal beds were tightly made. The 28 shower stalls were glistening. In a 200-seat cafeteria the chairs and long tables were neatly arranged.

After a month of remodeling that cost $350,000, an old Navy Department building was ready yesterday to serve as a shelter for the homeless in Anacostia Park. But exactly when it would open was still undecided.

"This is not going to be a Holiday Inn. It is not a fancy hotel," said C. McClain Haddow, chief of staff of the U.S. Department of Health and Human Services, who took reporters and a congressman on the first tours of the 600-bed shelter yesterday.

"But it is a clean, safe, habitable facility," Haddow continued, "far better than the one at Second and D Streets NW now, . . . even though it is not ideally located."

The federal government and the D.C. Coalition for the Homeless plan to use the new shelter until April 30 to house men who currently stay at the crumbling shelter downtown operated by the Community for Creative Non-Violence. But the plan has been strongly criticized by Mayor Marion Barry and by CCNV leader Mitch Snyder, who has asked a federal court to stop the government from closing the shelter that his group runs.

Yesterday Haddow said the new shelter would probably open within a week. The CCNV shelter, which is also in an old federal building, would probably be closed, he said, between a week and two months later.

"For all intents and purposes we're almost operational already," Haddow said. "But we want to do it in a sensitive way. There will be an appropriate transition time for the people to come here . . . . Then if some people are still there for political reasons, they'll have to be removed from the CCNV shelter because that would be trespassing."

Yesterday morning Haddow took Rep. Michael Barnes (D-Md.) on a tour of the shelter. The press was invited in the afternoon.

A spokesman for Barnes said the congressman will hold a subcommittee hearing today on the shelter controversy with Haddow and coalition leaders invited to appear along with Snyder, District officials, and residents of Anacostia who have objected to having the shelter "dumped" in their area.

Barnes believes the Anacostia shelter is "many times over better than the physical structure" at Second Street NW, said his press secretary, Bill Bronrott, but "it still does not satisfy the election-eve promise by President Reagan last year to provide a model shelter."

Exactly what Reagan promised and how it might be enforced has been the subject of the CCNV lawsuit, which is now before the U.S. Court of Appeals.