A potential function that describes the interaction between two hydroxylamine molecules has been developed from ab initio determined molecular properties and IMPT calculations for various dimer configurations using the 6-311G** basis set. The function comprises an electrostatic term in the form of a series of multipoles distributed over the atoms and an exponential repulsive term determined by fitting the results for the dimer. The dispersive term is expressed according to a London formula as a function of distributed spherical polarizabilities, and the contribution of induction is a function of the polarizabilities, distributed over the atoms. The proposed function reproduces the properties of the different minima for the hydroxylamine dimer with an accuracy similar to that of MP2 calculations. The electrostatic contribution predominates in all the configurations obtained, and the maximum possible number of X-H ... N hydrogen bonds is always favored. In addition, the function was employed to determine the lowest-energy configurations for the trimer, and the results were compared to those from ab initio calculations employing several methods.