According to a survey conducted by Rungsithong, Meyer, & Roath (2017), based on 156 partnership projects between buyers and suppliers in the Thai, they showed the importance of relational and economic attributes on firm performance as a mediate factor. The major purpose of this study was to explain how characteristics of a partnership effect relational capabilities that in turn enhance ?rm performance. The dependent variable of the study was performance, which was characterized by two dimensions; operational performances in terms of cost, quality and lead time and strategic performance, focusing on long-term consequences of the project such as the introduction of new product, technologies of markets. Operational performance was measured by the extent to which the buying company experienced process developments, especially in reliability, delivery, and flexibility while relational and economic attributes of a buyer-seller relationship, considered as the independent variable mainly focusing on long-term trust. Two intermediary variables, namely relational capabilities and complementary capabilities which orderly refers to knowledge sharing and ability of complementariness in partner organization. Also number of control variables have been adopted to analyze the links between these dimensions. The study has provided positive relationship under all hypothesis, which means based on the study of by Rungsithong, Meyer, & Roath (2017), inter-organizational trust has positive relation with knowledge sharing and complementary capabilities, similarly relationship specific assets have positive relation with knowledge sharing. Moreover, results suggest that knowledge sharing and complementary capability have positive relationship with operational performance, also operational performance has positive association with strategic performance. Finally, all together in confirms that there is a higher relation between relational quality, alliance capability and alliance performance.