In 1987-88 deep exploratory geothermal wells were drilled in the Asal Rift in the Republic of Djibouti. The salinity of the brines produced in the Asal field exceeded 100 000 mg/kg, with a low gas content of the order of 0.6 mmol/mol. Measured temperatures in the producing zones and at wellbottom vary from about 260 to 359 degrees C. The sphalerite and galena scaling observed in producing wells starts at the flash level located at about 850 m depth. The calculated geochemical temperatures are close to 260 degrees C, which is the average temperature of the main reservoir located at depths between 1000 and 1300 m. As a result of sulphide precipitation, about 90% of H2S is removed from the original fluid before discharge. The computed composition of the brine at reservoir conditions is compatible with the presence of stable phases of epidote, (Mg-Fe)-chlorite, albite, K-feldspar, K-mica, pyrite and anhydrite. The main recharge water is seawater.