A new apparatus optimised for the study of low-energy ion-neutral molecule collisions, designed and built in the University of Barcelona, is described in this Letter, as well as its use for the study, under single collision conditions, of the acetone-lithium ion system. The cross-section energy dependence in the 0.10-1.00 eV center of mass energy range has been measured in arbitrary units for the Li+-acetone adduct formation. Also, an empirical potential energy surface for the lithium-acetone adduct has been constructed and used to provide a qualitative interpretation of the reaction. (C) 2007 Elsevier B.V. All rights reserved.