A constant temperature box is disclosed comprising a body which is open at one side thereof having a lid for closing the open side of the body, the body and lid being of adiabatic construction. The box has incorporated therewith a container filled with a beverage which serves as a cooling or heating source to thereby cool or warm foodstuffs and beverages kept within a space inside the body, the beverage being readily discharged from the container by means of a valve or air pump.