In summary, it is shown that the AlInP(001) surface produced in the MOVPE environment is composed of a complete layer of phosphorus dimers. Half of the P dangling bonds on the dimers are hydrogen saturated, and the other half are filled with lone pairs of electrons. These lone pairs form a bound surface state slightly above the valence band maximum. DFT calculations suggest the existence of further structures, depending on the surface preparation conditions. P-rich surfaces are characterized by P dimers, while Al-P and In-P hetero-dimers form for more cation-rich surface preparation conditions. Most stable surface structures obey the electron counting rule. Dimer-related surface states are found close to the bulk valence band maximum. Exposure of the surface to extreme hydrogen-rich conditions is predicted to quench the dimerization and to remove all surface states from the region of the bulk band gap. For cation-and hydrogen-rich preparation conditions, metal atomic wires may form on the surface. They give rise to quasi-one-dimensional surface bands that pin the Fermi energy in the mid gap region.