Public-Private Partnerships (PPPs) have been emerged as a successful delivery approach for driving large-scale infrastructure projects to provide affordable services and to meet the public requirements. The successful development of performance-based output specifications (PSOS) for PPP infrastructure projects have been under the attention of many procurement agencies and public authorities. Many diverse groups from both public and private sector believe that the current practice of PSOS needs to be enhanced. The lack of guidance to ensure that the performance is properly linked with the designed end product is identified as the major challenge to develop a high quality PSOS. In this study, a set of performance criteria and a generic framework for developing high quality PSOS based on the hierarchy of system engineering approach is proposed. Moreover, two infrastructure projects were considered as case studies to evaluate the PSOS implemented and to compare the results obtained, with the proposed framework.