Purpose: The purpose of this study is to evaluate the status of eight interoperability protocols within repositories of electronic theses and dissertations (ETDs) as an introduction to further studies on feasibility of deploying these protocols in upcoming areas of interoperability. Design/methodology/approach: Three surveys of 266 ETD repositories, 15 common ETD management software solutions, and 136 ETD experts were conducted in order to appraise the protocols. These protocols were evaluated in four categories of aggregation, syndication, distributed search, and publishing protocols. Findings: This study revealed that, despite its drawbacks, Protocol for Metadata Harvesting (PMH) is still the most utilized interoperability protocol within ETD providers, ETD software developers, and implementers, followed by ATOM and Object Reuse and Exchange (ORE) protocols. However, in all competitive areas related to performance and functionality, ORE surpasses other protocols. It was also found that the three protocols of ATOM, PMH, and ORE could be used interchangeably in the most used cases of interoperability protocols in repositories. Practical implications: In this research, a combination of methods was employed to evaluate the status of protocols, from the perspectives of data providers, software providers, and implementers. Practitioners may use these methods to assess other protocols in terms of effectiveness and efficiency. Originality/value: The conduct of this study has involved three types of surveys, through which different aspects of interoperability protocols are evaluated. Prior to the conduct of this study, there has yet any study focusing on the same topic, which has adopted the multi-method that has been adopted in this study. (Contains 9 tables and 16 figures.)