A trader said that markets were maintaining firm levels, and added: "We did expect the JSE to open firmer on the stronger commodity prices. Resources have also performed quite well."
The trader said that banks, which were under pressure yesterday, have recovered.
"The US also looks set to open higher, so we're also following international markets," the trader added.
By 12:04 local time, the JSE all share index was up 0.79%, with platinum miners adding 1.76%, and gold miners rising 1.40%. Resources were 1.13% higher, and industrials rose 0.69%. Banks were 0.52% higher, while financials gained 0.31%.
The rand was trading at 6.82 to the dollar from 6.85 at the JSE's close on Monday. Gold was quoted at US$1 378.09 a troy ounce from US$1 369.50/oz at the JSE's previous close, while platinum was at $1 746.50/oz from $1 744/oz before.
Dow Jones Newswires reports that European stocks were mostly higher Tuesday, with banks leading the charge, as euro-zone sentiment improved after the Japanese finance minister said Japan plans to buy more than 20% of a bond offering by the European Financial Stability Facility this month.By 0910 GMT, the Stoxx Europe 600 index was up 0.6% at 280.26.
London's FTSE 100 was up 0.9% at 6 011.03, Frankfurt's DAX rose 0.3% to 6 878.59 and Paris's CAC-40 increased 0.4% to 3 818.68.
Despite the rises, some market commentators are still sceptical that Portugal will be able to continue without tapping into the EUR750bn European Union/International Monetary Fund facility.
"We are getting a deep sense of deja-vu with the emerging situation in Portugal," said Dermot O'Leary, economist at Goodbody Stockbrokers.
"Speculation has been building in the market at the start of this year that Portugal will be next in line to request aid, with the major trigger for that speculation the continued rise in Portuguese bond yields to well above rates that would be paid on an aid package from the IMF/EU.
The response from the Portuguese government has, unsurprisingly, been to deny that any aid request is forthcoming."
Meanwhile, sales updates following Christmas from the leading European retailers were coming in thick and fast. Marks & Spencer fell 0.8% to 381.10 pence. Although it beat its expectations and the Christmas sales offset some of the December snow disruption, many analysts were still disappointed.
German retailer Metro AG rose 0.7% to EUR53.0 after a 1.6% increase in fourth-quarter sales.
In Asia, stock markets were mixed Tuesday, with Australian stocks still struggling after the massive flooding in the state of Queensland.
Japan's Nikkei Stock Average fell 0.3%, Australia's S&P/ASX 200 was flat, South Korea's Kospi Composite gained 0.4%, China's Shanghai Composite increased 0.5% and Hong Kong's Hang Seng Index was up 1.0%.