The results of an angle resolved UPS study on K-CO coadsorbate on Cu(111) show that there is a molecular adsorption state of CO on the Cu(lll) with potassium at room temperature. The low 4σ/(5σ + 1π) intensity ratio suggests that the CO molecules inclined strongly in this state. Two adsorption states of CO are found at low temperatures (～150K). One of them appears for higher CO exposure (≥1L) only, and the other which exists for all (tcposures is similar to that at room temperature.