Solid state growth of intermetallic compound layers that form between hot dipped indium coatings and copper was investigated in diffusion couples aged at temperatures of 70, 100 and 135 degrees C and time periods of up to 300 days. At an annealing temperature of 70 degrees C, the metastable composition, Cu36In64, was observed at the interface. Ageing at 100 degrees C caused a dual layer structure with the Cu36In64 layer joined by a copper-rich intermetallic compound, Cu11In9, that is noted in the equilibrium phase diagram. An annealing temperature of 135 degrees C caused the eventual development of a single copper-rich intermetallic layer, Cu57In43, at the interface. Total intermetallic layer thickness was documented as a function of ageing time and temperature, exhibiting a t(1/2) dependence with an apparent activation energy of 20 kJ mol(-1).