'Force of Change'
Guebuza, who is running on a "Force of Change" ticket, only faces two challengers - Afonso Dhlakama, who heads Renamo, and Davis Simango, the MDM leader .
Dhlakama, who led the 16-year armed struggle against Frelimo, is also trying to court the foreign capital that helped the agriculture-dependent economy grow more than 6 per cent last year.
Expansion is forecast at 4.5 per cent for 2009.
Analysts expect Guebuza and his Frelimo to win a majority but not the two-thirds that would allow the party to change the constitution.
Gil Laureciano, a political analyst, said: "It's quite clear that he will win, but I don't expect him to get an absolute majority in parliament because most of the voters were neither born during the liberation struggle nor the devastating 16-year war against Renamo.
"They don't care about what happened in the past, so they will be voting for better job opportunities, for quality education and housing."
About 17 political parties and two coalitions are competing for ballots from Mozambique's almost 10 million registered voters.
"It is important to vote because it is to decide the future of the country, to give my opionion about how I want the future of the country to be," said Vasco Munguambe who had been waiting outside a Maputo poll station.
Early results from the more than 12,000 polling stations are expected to trickle in after polls close on Wednesday evening.