A water-soluble epoxy resin and hardener system for gelcasting of ceramics was developed. Polymerization of the system is a nucleophilic addition reaction, and not affected by oxygen. Therefore, this gelcasting system can be carried out in an air atmosphere. The ceramic slurries were prepared by mixing the aqueous premix solution of epoxy resin with alumina powder and dispersant. For cross-linking, a polyamine hardener was added. Both the rheological properties of the slurries and the gelling behaviors of the aqueous premix solutions were evaluated. The slurry with a solid loading of 80 wt% is optimized for gelcasting. The flexural strength of the sintered ceramics is 335 +/-47 MPa with 98% of theoretical density.