The authors over the last fifteen years have been involved in developing and refining a corrosion prediction model for multiphase CO2 / H2S oil / gas production and transmission environments. This paper evaluates the accuracy and efficacy of the current version of the prediction model in light of published validation data and field case studies. Corrosion rates from multiple field measurements including oil / gas production wells and transmission lines were evaluated utilizing the prediction model which incorporates extensive experimental data from comprehensive Joint Industry Projects (JIP) integrated with data from literature and field experience. Corrosion rates obtained from the prediction model are compared with actual field data to assess and quantify model accuracy. The sensitivity of certain reported parameters such as water analysis dew point and gas saturation to predicted in-situ pH and corrosion rates is also discussed.