Van der Waals interactions between the ground-state triplet O(3P) atom and the closed-shell HCl moleculeare investigated in the pre-reactive region. Three adiabatic (two of A‘ ‘ symmetry and one of A‘ symmetry)and four non-relativistic diabatic potential energy surfaces are obtained by combining a restricted open-shellcoupled cluster approach with the multireference configuration interaction method. The lower A‘ ‘ adiabaticpotential surface has a single minimum (De = 589 cm-1) for a linear O···HCl configuration. The upper A‘ ‘potential has a weak (De = 65 cm-1) minimum for a linear HCl···O configuration. The A‘ adiabatic potentialhas a weak (124 cm-1) T-shaped minimum. Adiabatic potentials intersect once in the O···HCl linearconfiguration and twice in the linear HCl···O geometry. The role of electrostatic interactions in shapingthese potentials is discussed. The effects of spin−orbit coupling on this interaction are also investigatedassuming a constant value of the SO parameter.