Economists had expected a gain of 0.6 per cent, according to Thomson Reuters.
Statistics Canada says higher sales were recorded in four subsectors, which together represent 72 per cent of wholesale sales, but the motor vehicle and parts subsector accounted for most of the increase.
That subsector rose 9.8 per cent to $9.3 billion, driven mainly by sales of motor vehicles, which were up 13.2 per cent. It was the third gain in four months for the motor vehicle industry and its largest monthly increase since November 2009.
The farm product subsector declined 5.0 per cent to $700 million after five consecutive monthly gains.
Sales increased in six provinces in May, with Ontario accounting for most of the gain.