We present the results of periodic DFT-GGA calculations on the HCl and HF ionization inside a cubic ice structure. The model considers the substitution of a water molecule by an HX molecule. The potential energy curves are drawn at fixed H-X distances. HCl dissociation inside the ice structure is a barrierless process, while HF presents a typical dissociation potential curve. The selected computational methodology is able to reproduce the experimental observations. (C) 2003 Elsevier Science B.V. All rights reserved.