The LAGROBO functional formulation of the interaction for four atom reactions is revisited and a strategy to fit the potential energy surface of the OH + HCl reaction to measured rate coefficients is discussed. The flexibility of the LAGROBO functional has allowed to keep the changes highly localized and to estimate the effect of varying the height of the barrier to reaction on the value of the related rate coefficients, An interesting agreement with the low temperature data is also found. (C) 2002 Elsevier Science B.V. All rights reserved.