The LOUHI82 program is a general purpose least-squares unfolding program. It is based on the minimization of the weighted square sum of the fitting errors of activities and several alternative terms related to the smoothness and assumed shape of the solution, allowing varying degrees of a priori information. The LOUHI82 program is a new version of the LOUHI-type unfolding programs, which have been used for fast neutron and high energy hadron spectrum unfolding. The number of energy points in the new version is 100, which makes it possible to simultaneously cover the intermediate and fast reactor neutron spectrum. In unfolding a reactor spectrum measured with an eight-component resonance and a nine-component threshold reaction detector, physically acceptable solutions were obtained using stronger and weaker a priori information.