The work described in this report (Volume I of a three volume set) was primarily done at Texaco's Montebello Research Laboratory, located near Los Angeles, California. It covers the first year of a five year program designed to demonstrate the integration of high temperature desulfurization with the Texaco Coal Gasification Process. Supporting work at MIT and at the Texaco Research Center in Beacon, New York is also briefly described. Theoretical studies and bench scale tests were done to identify in-situ and external high temperature desulfurization sorbents suitable for use with the Texaco Coal Gasification Process. For in-situ desulfurization, only iron oxide and the iron oxide/sodium oxide system had potential for success. PDU tests were made with iron oxide and iron oxide/sodium oxide in-situ sulfur sorbents. The results showed that 50--60% of the sulfur in the synthesis gas could be captured with either system, but the iron oxide/sodium oxide system produced extremely small solid particles which rendered the system inoperable. External sorbents tested in the PDU included zinc ferrite, zinc copper ferrite and zinc titanate. Of these, only the zinc titanate was found to be suitable. 34 figs., 26 tabs.