Interoperability is the ability of two or more systems or components to exchange information and use the exchanged information without special effort on either system. This paper attempts to propose a framework for evaluating and improving interoperability in each one of partners collaborating in a supply chain. The definition of the framework is based on three important hypotheses. The first hypothesis supposes the existence of interoperation activities which correspond with the part of business processes representing efforts for interoperability. The second one is the definition of Key Performance Indicators (KPIs) as aggregation of time, cost and quality performance for interoperation activities and also for actual business activities. The third one proposes to analyze impact of interoperability investments on enterprise objectives in two steps: the first step is the evaluation of the impact of interoperability solutions in KPIs; the second step analyzes the impact of improving KPIs in the achievement of enterprise's operational, tactical and strategic objectives. A methodology for prior evaluation of interoperability and improvement based on this framework is also proposed. The goal of this methodology is the validation of interoperability solutions to be implemented.