This note presents a new algorithm for estimating association parameters within molecular-based equations of state that allows the user to incorporate results from quantum chemistry. Using the simplified SAFT equation as an example, we show that the traditional parameter estimation approach (i.e., fitting parameters to vapor pressure and liquid density data) provides results that run counter to quantum chemistry findings on association strengths. Numerical results show that the parameter estimation approach proposed in this work provides a much more appropriate match to quantum chemistry results and gives markedly different amounts of site-site bonding. (C) 2008 Elsevier Ltd. All rights reserved.