Most Vaping products contain nicotine which is addictive and harmful to children, with the sale of such products highly regulated.
Town beat team officers and cadets visited five town centre stores with volunteer cadets attempting to buy products to ensure they were only selling to customers aged 18 or over.
Four cadets were denied sale without proof of age.
But one retailer sold a vaping product to a cadet aged under 18.
Melton Police said: “It is positive to see the majority of stores complying with regulations to protect younger people.
“If anyone has information regarding underage sales of prohibited items they should inform their local beat officer or trading standards department.”