The objective of this project is to update and advance an instrument necessary to conduct the trusted measurement of the concentration of dissolved oxygen in seawater by US and other international hydrographic programs. The Scripps Oceanographic Data Facility, a technical group operating under the Scripps Ship Operations and Marine Technical Support division and organized under Shipboard Technical Support, is responsible annually for thousands of measurements of dissolved oxygen performed on research vessels, while at sea, on bottles collected using classic hydrographic sampling techniques and measurement protocols. The majority of these measurements are for NSF funded programs and projects and constitute the reference-quality oxygen data for virtually all of the major NSF-funded global hydrography efforts that are the foundation of widely used databases. This award will allow continuation and improvement of these efforts through critical updates to a system that is ageing into obsolescence. Over the past 35 years Scripps has replicated and supported these oxygen titration systems for other oceanographic laboratories around the world. Many of these groups intend to either replicate the new design or hire Scripps to construct it through a service agreement. Leading the new design will allow Scripps to continue its role as an international leader in the collection and quality control of hydrographic oxygen data. As done for the past five years, technical experts will contin