As fellow delegates clustered behind her, the Rev. Imagene Stewart of the Church of What's Happening Now took the microphone to end the ceremony in the District Building yesterday.

Wearing a gold-encrusted silk outfit with her trouser legs tucked into black boots and sporting the tricolored hat bearing a "Free D.C." sign that most of the city's delegates to the National Women's Conference in Houston also were wearing, Stewart gave forth with an a cappella rendition of "I Am Woman."

It was a fitting end to the ceremony, which had attracted the city's politicians, a three-man band and a donated three-tiered cake decorated with red roses. Many women in the audience of about 90 clapped along with the minister, and everyone beamed.

The delegation - 12 regulars and five alternates elected at a city wide meeting earlier this year - is flying to Houston later this week at government expense to attend the conference. The purpose of the Houston meeting is to discuss barriers to women's equality and propose legislation to eliminate them.

"This delegation is going to keep it together!" said Bennetta Washington, who followed her husband Mayor Walter E. Washington, to the podium. Mrs. Washington, who actually is Dr. Washington, also is attending the conference as an at-large delegate.

Yesterday's celebration also was to mark the 10th anniversary of the D.C. Commission on the Status of Women, which soon will have its name changed if legislation announced by Mayor Washington as a birthday present yesterday is approved. It would become the Commission for Women and have statutory authority.

The delegation to Houston has taken the cause of self-determination for the District of Columbia as one of the major issues it hopes the conference of more than 2,000 people will support. Although the group plans to circulate petitions and lobby to gain such support, delegates from other state have said they do not understand why self-determination for the District is a women's issue.

"Because the District is over 53 per cent women, and we are not represented in Congress, that's why," said Anne B. Turpeau, who is chairperson of the delegation and of the commission.

Among the city delegates are feminists, four avowed lesbians who consider themselves strong feminists, blacks and one Puerto Rican.

Included are Etta Horn, mother of seven and an organizer of the D.C. Welfare Rights Organization who runs a day-care center, and school board member Barbara Simmons who noted in her conference biography that "my area of emphasis is strategies for change."

Also attending will be May Spottswood Pou, who was at the 1975 conference of radical feminists and works for the National Electrical Manufacturers Association, and Ruth A. Sykes, who works for the National Council for Negro Women.

Mayor Washington told the delegates: "As you go to Houston, you go with a government solidly behind you. I know you're going to be careful about what you say . . . the entire city and the government stands behind you on any proposition."