A program to determine if concrete polymer materials can be utilized as materials of construction in geothermal processes is in progress. To date, several high temperature polymer concrete systems have been formulated, laboratory and field tests performed in brine, flashing brine, and steam at temperatures up to 260/sup 0/C (500/sup 0/F), and economic studies started. Laboratory data for exposure times up to 2 years are available. Results are also available from field exposures of up to 12 months in four geothermal environments. Good durability is indicated. Work at two of these sites is continuing and tests have recently been initiated at two locations in the Imperial Valley. Work accomplished during the period January 1 to March 31, 1977 is described in the current report.