Abstract: An improved anti-corrosive zinc coating composition for application on a metal substrate is provided. The coating is comprised of a siloxane polymer resin in combination with zinc dust and ceramic microspheres, the microspheres having diameters of 45 microns or less. At this reduced diameter, the microspheres act as spacers for the zinc particles without interfering with the conductivity of the coating, thereby reducing the amount of zinc necessary to achieve cathodic protection of the substrate. The coating is economical to produce, provides excellent corrosion protection, and resists mud-cracking.