Peter O'Neill's People's National Congress won the last election in 2012, he seeks another term to fix an economy under siege.
Peter O'Neill's People's National Congress won the last election in 2012, and he has campaigned on delivering key infrastructure and providing free education and health to a country that remains mired in poverty.
He also points to more stability in a sprawling crime-ridden land where elections have been marred by violence in the past.
"I appeal to all our citizens to peacefully cast their votes," said the prime minister, with more than 3,000 candidates from over 40 political parties jostling for support.
"Let’s show the international community that PNG has come of age and will express its democratic principles in a manner acceptable to the community."
Polling for the 111-seat parliament runs for two weeks until July 8 with staggered voting across the vast and remote country. A result is not expected until late July.
There is no opinion polling in PNG, so it is unclear who holds the advantage.
But no party has ever won a majority, meaning a coalition is likely, held together by strategic political appointments.
O'Neill's main threat is seen as Don Polye's Triumph Heritage Empowerment Party.
Opponents accuse O'Neill of mismanaging an economy hurt by slumping global commodity prices, racking up debt by recklessly spending to meet his goals.
He has also been tarred by corruption allegations, surviving a no-confidence vote last year following weeks of protests and civil disobedience urging him to resign.
PNG's largest aid donor Australia has been working closely with Port Moresby to ensure the polling passes off smoothly, supplying election experts to train 30,000 local staff.
It has also provided military helicopters and planes to help transport election materials to remote areas of a mountainous country that has some of the world’s most difficult terrain.
Hundreds of observers are in the country monitoring the polls, watching for any vote-buying as candidates jockey for a position in government.
PNG villagers, who receive little from the political system, often see elections as simply a "time of food" -- a reference to the cash, pigs and other items candidates provide to win votes.
"We will consider whether the elections have been conducted according to the standards for democratic elections to which Papua New Guinea has committed itself," said Commonwealth Observer Group chair Anand Satyanand on the role his team was playing.