Speaking on the 50th anniversary of the trial at the Palace of Justice in Pretoria's Church Square, where the original trial was held, Kathrada gave a graphic account of the time he spent there.
Kathrada, along with 10 leaders of the African National Congress, were sentenced during the trial for sabotage to overthrow the apartheid system.
He explained the dreaded 90-day detention law, in which prisoners were held in isolation with no contact at all with the outside world.
"You are sitting alone in your cell. The only thought is death. Make no mistake about it - your thoughts are about yourself - 'am I going to die?'," Kathrada said.
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He described how they saw Mandela at the trial after a year because he had already been sentenced in another trial.
"We saw him come there with short pants and sandals and he was a shadow of himself. He had lost a lot of weight in the year that he was in prison before us. But his spirit was there; as strong as ever."
"I think that the Rivonia Trial has overshadowed many other trials, which is not consistent with the struggle in this country.
"What about the 'Little Rivonia' trial in which Mac Maharaj was involved, and others?" Kathrada asked.
"Among the eight of us who were sentenced to life imprisonment, there were four of the most senior ANC leaders in the country - Madiba, Walter Sisulu, Govan Mbeki and Raymond Mhlaba - and it was great blessing to have them among us in the trial and (later) on Robben Island.