The hybridization of carbon atoms in C2H2 is sp. This means that each carbon atom in C2H2 has two sp hybrid orbitals and two p orbitals. The sp hybrid orbitals are formed by the mixing of one s orbital and one p orbital, and they are directed away from each other at an angle of 180 degrees. The p orbitals are perpendicular to the sp hybrid orbitals, and they are also directed away from each other at an angle of 90 degrees.