In a method of forming a metal oxide, an organic metal compound represented by the following chemical formula is introduced into a chamber to chemisorb the organic metal compound onto a substrate, M[L1]x[L2]y where M represents a metal, L1 and L2 respectively represents a first and second ligands. In addition, x and y are independently integers and a value of (x+y) is 3 to 5. An oxygen-containing compound is introduced into the chamber to form the metal oxide. The metal oxide is formed by reacting an oxygen of the oxygen-containing compound with the metal, and separating the ligand from the metal. Thus, the metal oxide having a superior step coverage and a high dielectric constant may be formed using the organic metal compound by an atomic layer deposition process.