Vapor-liquid equilibrium (VLE) measurements were conducted for both unloaded and CO2 loaded aqueous amine amino acid salt (AAAS) solutions; 3-(methylamino)propylamine/sarcosine (SARMAPA). Vapor-liquid equilibrium for unloaded solutions for 1.0-5.0 M SARMAPA were measured using a Swietoslawski ebulliometer for temperatures 40-100 degrees C and for total pressures 4.08-99.1 kPa. CO2 equilibrium was determined for loaded 5 M SARMAPA using low and high temperature VLE apparatuses from 40 to 120 degrees C. A thermodynamic model representing equilibrium in the H2O-AAAS-CO2 system was developed using the extended UNIQUAC thermodynamic framework. The developed model predicts simplified speciations in H2O-SARMAPA-CO2 system and adequately correlates the experimental total and partial pressure data with an average absolute deviation of 8.9%. (C) 2011 Elsevier Ltd. All rights reserved.