Martin Guptill returned to form with an unbeaten century as New Zealand powered to an eight-wicket win over Bangladesh in the first one-day international in Napier on Wednesday.

Bangladesh set New Zealand a modest run chase of 233 after suffering an early collapse and the Black Caps overhauled it in 44.3 overs, finishing at 233 for two.

It is Bangladesh's fifth tour to New Zealand and they are yet to win a match in any format, with their next chance coming in the second ODI in Christchurch on Saturday.

Bangladesh captain Mashrafe Mortaza said his team were adjusting to New Zealand conditions and still hoped of a breakthrough victory.

"We bowled well but we were struggling batting. We just lost too many wickets early," he said.

Guptill and Henry Nicholls pressed their case to open the batting at the World Cup as New Zealand made light work of the target.

Guptill, returning from injury, put a poor run of scores behind him with a commanding 117 not out.

His 15th ODI century came off 103 balls and included six fours and three sixes.

Nicholls looked comfortable in just his third outing since being promoted up the order, scoring 53 before a tame dismissal when the ball hit his pad and rolled onto the stumps.

Veteran batsman Ross Taylor also contributed an unbeaten 45.

Mohammad Mithun was the pick of Bangladesh's hitters, grinding out a hard-fought 62 after coming to the crease with Bangladesh reeling at 42 for four after a decision to bat first backfired.

Mohammad Saifuddin provided support with a gritty 41 as Bangladesh were bowled out for 232 with seven balls of their allotted 50 overs remaining.

Spinner Mitchell Santner and paceman Trent Boult took three wickets apiece for New Zealand.