We have studied the atomic and electronic structures of submonolayer In on Cu(111) using synchrotron radiation photoemission and scanning tunnelling microscopy. At very low coverage, In atoms were favourable to occupy substitutional sites and to be distributed evenly on the Cu(111) surface. At a higher coverage of 0.33 and 0.50 ML, two ordered reconstructed phases of (√3 × √3)R30° and (2 × 1) have been observed for the first time. The two-dimensional states of In-induced valence bands in the (√3 × √3)R30° phase were measured by angle-resolved photoemission. The result is in good agreement with theoretical calculations.