The General Elastic Analysis of the bending of a bi-metallic strip subjected to uniform heating has been made by Timoshenko. In this note we extend the theory to that of a tri-metal strip. General formulae for curvature and bending stresses have been developed. These formulae reduce to simple expressions if a particular choice of material constants and thicknesses is made. These latter formulae indicate that the curvature can be independent of the coefficient of linear expansion of the middle material and that it is possible to have the stresses at the inter-surfaces equal if a proper choice of the ratios of the coefficients of linear expansion of the three materials is made.