The surface properties of several glass-ionomer restorative dental materials (GC Fuji, Chemadent G-J, Ketac Fil and Ketac Molar) were investigated by means of inverse gas chromatography. The capacity of the surface of glass-ionomers to undergo specific interactions was expressed using the specific component of free energy &UDelta; G(s) as well as the parameters K-A and K-D to describe the ability of the cement to act both as an electron acceptor and an electron donor, respectively. The character of the examined surface was expressed with the use of the S-C parameter. All these parameters were determined with a high degree of precision. It was found that the surface of glass-ionomer cements had a well-marked acidic character. The ability of the cement surface to take part in specific interactions differed with the various types of commercial products. The surface activity of the glass-ionomers investigated changed with the storage time (up to 6 months) indicating an on-going setting reaction. © 2004 Elsevier B.V. All rights reserved.