The coffee chain is trying out a new dark roast coffee in addition to its regular blend at locations in London, Ont., and Columbus, Ohio.
It is the first time in the company's 49-year history that it has offered a new blend of coffee.
The new blend will be made from 100 per cent Arabica beans and cost the same as the chain's regular blend.
The choice comes as Tim's rivals including McDonalds and Starbucks have turned up the pressure with discounts and customer loyalty programs.
Tim Hortons chief executive Marc Caira has been conducting a widespread review of the chain's operations since taking over earlier this year.