A sting targeting vape retailers in Barrow and Ulverston found two stores selling to under-18s.
Trading Standards visited five traders in the towns with a young test purchaser and two of them sold e-cigarettes to the youngsters.
The operation was carried out by the Westmorland and Furness team following several complaints from concerned parents, schools, and members of the public.
It is a criminal offence to sell nicotine vaping products to under-18s, or purchase them on behalf of under-18s. Traders found breaking these rules risk being prosecuted, and a possible maximum £2,500 fine.
More operations will be carried out over the coming months, the council said.
