Security forces detained between 50 and 60 protesters in clashes on Friday in the Omani industrial town of Sohar, witnesses said.
The violence on Friday during a fifth week of protests involved the use of knives, stones, teargas and rubber bullets, Oman's general prosecutor said.
It came three days after a crackdown against protesters to clear a Sohar roundabout where about 100 people had camped out.
A 25-year-old man injured by a rubber bullet in Friday's clashes died in hospital. Activists told Reuters security forces used teargas and beat some protesters with batons.
Oman's general prosecutor said in a statement carried by state media that demonstrators, some of whom were demanding the release of protesters detained on Tuesday, threw stones and used knives against security forces who used teargas and shot rubber bullets to disperse them.
Some protesters shot back at officers, the statement said, adding that five protesters were wounded, one critically.
In the capital Muscat, about 150 people gathered outside the Shura Council, the elected chamber of parliament, late on Friday but there was no visible security presence, a Reuters witness said. A few dozen remained on Saturday.
Organisers said they were waiting for more protesters to arrive from Sohar and planned to march on government offices later in the day.
Protests against autocratic rulers sweeping the region have not spared conservative and usually tranquil Oman, at the southeastern end of the Arabian Peninsula. The ruling dynasty has long been backed by Washington and also has ties to Iran, a US rival for influence in the region.
Protests in Oman, which pumps out 800,000 barrels of oil a day, have focused on demands for better wages, jobs and an end to corruption. Many protesters have demanded that the government be held accountable for the detention of hundreds of demonstrators in Sohar.
Some of the protesters at the roundabout on Friday had set up road blocks and were charging drivers tolls, witnesses said, saying they were jobless and needed the money.
Two roundabouts 15 km (nine miles) apart have been the centre of the protests in Sohar. Each was guarded by two armoured vehicles on Saturday.
Wealthy Gulf Arab oil producers launched a $20bn aid package this month for their less prosperous neighbours, Oman and Bahrain, a measure intended to generate jobs and that should enable the two countries to upgrade housing and infrastructure.
Bahrain's Sunni rulers have stepped up arrests of cyber activists and Shiites, with more than 300 detained and dozens missing since security forces broke up pro-democracy street protests last month.
Bahrain imposed martial law and called in troops from fellow Sunni-ruled neighbours, including Saudi Arabia, to quell the protest movement led mostly by the state's Shi'ite majority.