Woodward & Lothrop Inc. and Quadrangle Development Corp. disclosed plans yesterday to build a $195-million hotel, office and retail project on the block north of Woodies' big downtown store.

The 12-story complex, to be started next year, will occupy the entire block bounded by 10th, 11th, G and H streets NW, Quadrangle President Robert Gladstone said.

On the north side of the block, facing H Street, Quadrangle plans a hotel with as many as 1,000 rooms to serve the D.C. Convention Center now being built on the north side of H Street. "This will be the headquarters hotel for the convention center, as we envision it," added Gladstone, who said his firm is negotiating with several hotel companies to operate the facility.

A through-the-block arcade will provide a direct link from the convention center to the Metro subway station beneath G Street, Gladstone said. The south half of the block will be occupied by an office building and a two-level shopping mall built around an atrium.

Woodies, which owns about three quarters of that block, will swap its property with Quadrangle in exchange for a new office and service building to be built elsewhere, said Edwin K. Hoffman, chairman of the department store group.

To make way for the new construction, Woodies will close its old "North Store" building, now used primarily as a seasonal sales center, offices and workrooms, Hoffman said. The main Woodward & Lothrop store, on the block bounded by 10th, 11th, F and G streets, will remain the flagship unit for Washington's biggest general merchandise retailer.

Quadrangle said the project will include parking for about 500 cars and about 1.35 million square feet of office, hotel and retail space. It will be nearly as large as the 1.5-million-square-foot mixed-use development Quadrangle is putting up at Pennsylvania Avenue and 14th Street, adjacent to the National Press Building and National Theater.

Woodies' north-block project is across 10th Street from Metro Center, an even bigger retail and office development being built atop the Metro Center subway station by the Oliver T. Carr Co. Carr is negotiating with The Hecht Co. to build a new downtown store in that project.

Quadrangle's construction schedule calls for starting work on the north side of the block next year, leaving Woodies north store and parking ramp in operation. Before the hotel is finished, work will start on the rest of the project so both can be completed in 1985, Gladstone said.

A letter of intent signed by Hoffman and Gladstone provides for Quadrangle to pay Woodward & Lothrop a total of $33.1 million for the downtown land. Much of the payment will be in the form of the new Woodies building to be developed by Quadrangle. No site has been selected for the new building, Hoffman said.

Hoffman said the sale of the north store site is part of a corporate strategy of "maximizing use of our real estate." He told stockholders recently that Woodies "is sitting on a gold mine" in land adjacent to its downtown and Chevy Chase stores and those properties could have a major impact on future profits.

Until a final agreement is signed with Quadrangle, it will not be possible to calculate how much Woodies will make on the downtown land sale, he added.

Woodies will not participate in development of the downtown land, but it is partners with Quadrangle in a venture to redevelop the parking lot adjacent to the Chevy Chase store just outside the District line at Wisconsin and Western Avenues NW.