A portable cooling apparatus for cooling a keg has a cylindrical or truncated cone shaped sleeve made of semi-rigid water-proof material which is open at both ends. The sleeve is slipped over the keg and clamped at its lower end to the lower portion of the keg with a barrel lock or strap. The upper end faces upward and is flared open by the semi-rigid structure of the sleeve material, which allows ice to be filled in and packed directly around the sides of the keg. The sleeve can have pleats or slats at its lower end which are gathered around the keg, and a drainage spout for allowing water to drain out from the lower end of the sleeve.