Wilhelm Ostwald in 1894 introduced mole concept.
Mole concept was basically introduced in order to compare the relative quantities in which reactants react and products were obtained in a simpler manner. We know that atoms and molecules are extremely small quantities, so even a small quantity of reactant or product would mean a large number of atoms or molecules. Hence, chemical reactions when spoken in terms of number of molecules of reactant or products would become very tedious. Thus in order to simplify this the mole concept was introduced. Also, there is no ambiguity about the amounts in which the reactants react and products are formed.