Critical equipment in high pressure high temperature (HPHT) oil and gas wells are commonly made of superalloys. Components in these wells require both high strength and corrosion resistance. In this study, four superalloys: Elgiloy (UNS R30003), MP35N (UNS R30035), Alloy 718 (UNS N07718) and 945X (UNS N09946) were tested in an environment with H2S, CO2, and high chlorides. Four-point bend tests were performed with N07718 and UNS N09946 materials while three-point bend tests were done on UNS R30003 and UNS R30035 in an autoclave with pH2S of 0.025 bar and pCO2 16.6 bar, and 308 g/L Cl- at 363°F for 30 days. Neither cracking nor pitting was observed on any of the four-point or three-point bend specimens. In addition to four-point bend testing, slow strain rate tests were performed on UNS N07718 and UNS N09946 materials. Results of the slow strain rate test showed no significant decrease in ductility in either UNS N09946 or UNS N07718. However, UNS N09946 performed better than UNS N07718 in a high chloride environment based solely on SSRT results.