The union, Nehawu, declared a dispute after Unisa refused its demand for a 12% salary increase across the board. The university is offering 8.5%.
"The negotiations have been going on since the beginning of the year and we have tried every trick in the book, but they are not prepared to move," said Nehawu spokesman Sizwe Pamla.
The protest, involving academic and support staff, started at 9am. The union was communicating with the provincial leadership to ensure that the protest spreads nationwide today, said Pamla.
"They have told us that they will implement the 8.5% as of Friday, whether we agree or not. That is why we decided to embark on the strike."
Unisa spokesman Lehuma Ntuane said the university management believed that its offer was more than generous.
Bonuses and pay progressions were not ordinarily paid at tertiary institutions and should be seen as an additional benefit for Unisa employees, Ntuane said.
"We have not only the salary increments but performance-related bonuses too."