Abstract: The present invention relates to an improved heat curable epoxy resin adhesive in which a metal oxide, for example zinc oxide, and a polyhydroxyaryl compound, for example gallic acid, are used in combination with an epoxy resin, for example a heat curable liquid epoxy resin adhesive, to give an adhesive composition having significantly improved binding strength and resistance to weathering. The epoxy resin adhesive composition of the invention has been found to be particularly advantageous in the bonding of metal surfaces providing higher bond strength over a prolonged period and improved resistance to the deterioration of bond strength in the presence of water or high humidity.