Around 35 businesses have signed up to Sheffield Council's "responsible retailer" scheme and will receive certificates from the Lord Mayor, Councillor Alan Law, tomorrow.
The aim of the scheme is to restrict children's access to products such as tobacco, alcohol, solvents, knives and fireworks.
Greg Ward from Sheffield Council's trading standards team said: "Unfortunately, in today's society it is becoming increasingly difficult to determine the ages of young customers and teenagers are becoming more and more confident, even aggressive, in their pursuit of age-restricted products.
"When confronted by a young customer, retailers are advised to ask to see a recognised identification card or document bearing a current photograph and date of birth of the holder, as proof of age.
"We have produced a pack containing information on age-restricted products and the laws around their sale to help retailers train their staff to conform to under-age sales legislation. This has been distributed free of charge."