Open innovation has been a subject of major interest in technology management in recent years. Innovation intermediaries are considered to be an important part of open innovation. In this paper, we investigated the Industrial Technology Assistance Program (the so-called iTAP), one of the innovation intermediaries for small and medium enterprises (SMEs) in Thailand. The study identifies challenges facing by both SMEs and innovation intermediaries and offers major key success factors, which consist of competent people, problem identification, proper resource allocation, effective planning, strong alignment and management support, for the improvement of such operations. The contribution from the study could be useful for practitioners and academia of open innovation to enhance their operational efficiency and develop a better understanding and/or theoretical framework for open innovation.