Thermal waters from the Rif (Northern Morocco) have temperatures in the 31-52 degrees C range, near-neutral pH (6.3-7.0), variable redox conditions (from -0.2 to 0.5 V) and a wide range of total dissolved solids (<1-27 g/l). The D/H and O-18/O-16 isotopic ratios of the water suggest a meteoric origin for the thermal waters. The main chemical composition is sodium-chloride, resulting from the interaction of water with marine sediments. High salinity waters show high concentrations of B, Li, and Sr, while other minor components and metals (e.g., Fe, Mn, Zn, Cd, Pb, Cu, Co, Ni, As, Sb and Hg) are usually very low. At Oulmes (Massif Central) the water shows 42 degrees C, a pH of 5.9. TDS of 1.5 g/l, sodium-bicarbonate chemical composition, and high P-CO;; This water flows out of granite rocks and is characterised by high concentrations of SiO2, Li, Rb, Cs, Fe, Mn, Be and As. Chemical equilibrium studies show that the thermal waters are close to equilibrium with respect to calcite, dolomite, chalcedony and kaolinite, while equilibrium with respect to gypsum and barite occurs in the sulphate-rich waters. Chemical geothermometers suggest deep temperatures close to 100 degrees C for the warmest water in the Rif (RAY Yacoub: 52 degrees C at the emergence), and about 130 degrees C at Oulmes. (C) 2000 CNR.