The partnership of Hilda Bernstein, who has died in Cape Town aged 91, and her husband, Lionel "Rusty" Bernstein (obituary, June 26 2002), featured long and enduringly in the struggle against apartheid, both in South Africa and in their English exile. Perhaps Hilda's most unprecedented accomplishment was to persuade white voters to elect her, a communist, to the Johannesburg city council. But that was 1943, before Hilda and communism were red-carded by the Afrikaner nationalist referee.

Hilda Bernstein was an all-rounder - she could "talk the talk" (through her books and rousing oratory) and "walk the walk" (she was a founder, in 1956, of the non-racial Federation of South African Women; and had a conviction, in 1946, for involvement in a black mineworkers' strike). But alongside her feminism was a devotion to her home and her four children. A colleague at the Johannesburg publishers where Hilda edited a family magazine, recalls her rushing home early to make naartjie (mandarin) marmalade.

Hilda Watts grew up in London's East End, the daughter of Jewish Russian emigrants. Her father, Simeon Schwarz was a Bolshevik and was made the Soviet trade attaché in London in 1919, but was recalled to Moscow in 1925, never to return. His widow, Dora, emigrated to Johannesburg with Hilda, the youngest of the three daughters, in 1932. Hilda was quickly active in the youth branch of the Labour party, but in 1940 joined the Communist party. A fine public speaker with an exceptional organisational ability, she was elected to the council by the voters of Hillbrow, the most (or only) avant garde of the suburbs, and certainly helped by South Africa being an ally of Moscow. But it gave her a further insight into the woeful plight of urban Africans, particularly the migrant gold miners.

Throughout the 1950s, Hilda worked tirelessly to better the condition of African women, despite being banned from 28 organisations. She helped organise the march in 1956 in which 20,000 women converged on the Union Buildings, the seat of government in Pretoria, to demonstrate against the pass laws. And she was a founder and national secretary of the Peace Council until it, too, was banned. But there were ways to carry on the work clandestinely, but when, in 1958, her writing and magazine work was banned, it was a serious financial blow.

She had married Rusty, an architect, in 1941. He had drafted the Freedom Charter, the founding document of the liberation struggle. But his ability to pay the bills for a growing family was likewise hindered by political intrusions, notably the four years, 1956-60, as a defendant in the treason trial, and then his and Hilda's detention in the State of Emergency that followed the shootings at Sharpeville in 1960.

And yet they managed. In her book The World that was Ours (1967), she recounts that their house in Observatory "breathed and murmured with people and sound - people coming to swim, to talk, to borrow books, the children's friends of all ages; people who never rang the bell or knocked, but called a greeting as they came in." The house "shines brightly at us from one side of the mirror; on the other are the homes and lives of our friends and comrades in the [black] locations".

Rusty was the sole accused in the 1964 Rivonia trial to be acquitted. Nelson Mandela, Walter Sisulu and other ANC leaders were jailed for life. He was immediately re-arrested, then surprisingly bailed, giving the couple the option of quitting a hopeless political stage. And yet the decision was agonising. As the police closed in, Hilda still did the housewifely thing, and took the clothes out of the washing machine and then slipped out through a secret passage in the back garden. They were taken across the border into the then British Bechuanaland and arrived in England in their forties.

Rusty worked as an architect, while Hilda launched a career as a graphic artist. She created book covers, and African National Congress and Anti-apartheid Movement posters and greeting cards, and combined that with shows of her etchings around the world. She also chronicled the big story with books on the women's struggle, For Their triumphs and Their Tears, 1978; the murdered activist, Steve Biko, No 46 - Steve Biko, 1978; and a series of interviews on her countrymen and women's experience in exile. Her novel Death is Part of the Process (1983) won the Sinclair prize and was made into a BBC drama. Those who heard her at meetings were left in no doubt about the seriousness of events in South Africa. After the Soviet invasion of Czechoslovakia, in 1968, she left the Communist party.

They moved from London to Herefordshire in 1981 where guests enjoyed the conversation and the cuisine, though non-smokers endured a ban on the weed as unalterable as an edict from Pretoria. They returned for a visit to South Africa in 1994 to work for an ANC victory.

They were living in Kidlington, near Oxford, when Rusty died. Soon after, Mandela, on a visit to Britain, drove over to talk about old times. In 2003, Hilda returned to South Africa and lived in a flat in the Cape Town seaside suburb of Sea Point, near her son Keith.

Last week her doctor told her there was not long to go. She phoned her children in Europe to say goodbye. She is survived by children, Toni, Patrick, Frances and Keith, seven grandchildren and four great grandchildren.

· Hilda Bernstein, political activist, born May 15 1915; died September 9 2006