To facilitate advances in application of technologies pertaining to gas hydrates, a United States database containing experimentally-derived information about those materials was developed. The Clathrate Hydrate Physical Property Database (NIST Standard Reference Database # 156) was developed by the TRC Group at NIST in Boulder, Colorado paralleling a highly-successful database of thermodynamic properties of molecular pure compounds and their mixtures and in association with an international effort on the part of CODATA to aid in international data sharing. Development and population of this database relied on the development of three components of information-processing infrastructure: (1) guided data capture (GDC) software designed to convert data and metadata into a well-organized, electronic format, (2) a relational data storage facility to accommodate all types of numerical and metadata within the scope of the project, and (3) a gas hydrate markup language (GHML) developed to standardize data communications between "data producers" and "data users". EXECUTIVE SUMMARYTo facilitate advances in application of technologies pertaining to gas hydrates, a United States database containing experimentally-derived information about those materials was developed. The Clathrate Hydrate Physical Property Database (NIST Standard Reference Database # 156) was created by the Thermodynamics Research Center (TRC) Group at the National Institute of Standards and Technology (NIST) in Boulder, Colorado. The database development paralleled that of a highly-successful relational database of thermodynamic properties of pure molecular compounds and their mixtures (SOURCE) that is maintained by TRC at NIST. The project was completed in association with an international effort by the Committee on Data for Science and Technology (CODATA) to aid in international data sharing. Development and population of the new database relied on the development of three components of information-processing infrastructure: (1) Guided Data Capture (GDC) software designed to convert data and metadata into a well-organized, electronic format, (2) a relational data storage facility to accommodate all types of numerical and metadata within the scope of the project, and (3) a gas hydrate markup language (GHML) developed to standardize data communications between "data producers" and "data users", i.e., the academic and industrial research communities.Guided Data Capture (GDC) software was developed for this project with specific application to characterization and properties of gas hydrates. This software was and continues to be utilized in the data collection process to aid technically competent individuals, typically student associates, who are not expert in data collection and measurement technology in capturing all relevant information from a literature source. The captured information is used by staff experts to produce optimally accurate properties with reliable uncertainty estimates.The NIST/TRC Gas Hydrate Data Entry Facility was establis...