Zuma, who was ousted as head of state in February, attended a brief preliminary hearing at the high court in Durban, a city on the south-east coast.
Referred to as Accused Number One, the 75-year-old did not speak, but told cheering supporters outside court: “The truth will come out. What have I done? I am innocent until proven guilty.”
Hundreds of supporters, many dressed in the green and gold of the ruling African National Congress (ANC) party, had gathered to chant and sing slogans, and a large police presence had been deployed to prevent clashes.
Some carried placards saying “hands off Zuma” and performed the high-stepping toyi-toyi protest dance made popular in South Africa’s decades-long struggle against apartheid.
The case was adjourned until June. The hearing is likely to be the first of many as the former president fights a possible jail sentence.
Analysts say the case is a key test of Zuma’s ability to rally the more radical elements within the ANC or on the political fringes, as well as support in the important province of KwaZulu Natal (KNZ), his political power base.
“If he allows his supporters to turn up the heat that is a possible indication that he is still willing to put his interests before those of the ANC,” said Richard Calland, an author and expert on South African politics.
The trial will also indicate how difficult it will be for the new president Cyril Ramaphosa to succeed in his attempt to restore the ANC’s battered image.
Zuma’s nine years in office were marked by economic stagnation, soaring unemployment, multiple corruption scandals and credit downgrades.
The popularity of the ANC, in power since South Africa’s first free elections in 1994, has flagged in recent years, with significant defeats at municipal polls in 2016. A general election will be held next year.
Since taking power, Ramaphosa has reshuffled the cabinet, firing ministers close to Zuma tainted by corruption allegations. It has also moved to reform major state utilities as well as a revenue collection service. A recent budget pleased international investors, boosting the rand.
“So far, Ramaphosa has not put a foot wrong. Some achievements were certainly low-hanging fruit but are still very important. At the very least, [the trial of Zuma] is a major distraction … [and] there is a risk it could undermine progress already made,” Calland said.
“The downside of cleaning up government and corruption is that as further evidence of wrongdoings emerge and the perpetrators are caught and prosecuted, it reminds people of what went wrong and creates more people who can cause trouble … for the new president.”
Since Ramaphosa, seen as the leader of the ANC’s moderate, pro-market faction, took power, many analysts are more positive about growth in one of the continent’s most important economies.
The case against Zuma centres on 783 individual payments from his former financial adviser, Schabir Shaik, who was jailed for corruption in relation to the arms deal.
Charges against Zuma were filed but then set aside by the National Prosecuting Authority shortly before he successfully ran for president in 2009. The charges were reinstated in 2016. A summons was issued to Zuma within weeks of his ouster.
Since his election nine years ago, the former president’s opponents have fought a lengthy legal battle to have the charges reinstated. Zuma denies wrongdoing and has countered with his own legal challenges.
Zuma’s son Edward told supporters at a park in Durban where several thousand people held an overnight vigil before the court hearing that his father was not worried.
“I would want to believe that as an innocent man, he is definitely not worried,” the domestic News24 agency quoted him as saying.
One supporter said he admired Zuma’s determination to bring in economic policies during his time in office that he said were designed to spread the wealth in what remains one of the world’s most unequal societies.
“Whatever happens we will still support Zuma because we believe he brought us radical economic transformation and we still believe that him being in the ANC, he will push for it,” said businessman Siya Khoza outside the court.
Zuma has claimed he is being victimised. “People are free, but I am not. They are still after me,” he said after an Easter church service.
Campaign groups are hoping that the case could set a benchmark for future prosecutions.
“The arms deal wasn’t just about small bribes, it launched the bullet and we watched that bullet in slow motion ripping through South African democracy in the last 15 years,” said Hennie van Vuuren of the Open Secrets anti-graft association.
There is “overwhelming evidence” of Zuma’s guilt, former ANC MP and anti-corruption activist Andrew Feinstein said.
“The reality is that Jacob Zuma should find himself in jail,” Feinstein told AFP.
THE GUARDIAN UK