The tropical atmosphere plays a major role in the climate dynamics, through the influence of water vapor and clouds on the radiative budget of the Earth, and the release of latent heat in rainy systems. Present operational satellites do not allow reliable estimations of atmospheric water parameters, because they suffer from inappropriate instrumentation (geosynchronous) or from insufficient sampling (polar orbiters). TRMM is the only scheduled mission devoted to the tropics, but will still provide an insufficient sampling. Small satellites may alleviate these problems by placing several key passive instruments into appropriate orbits. TROPIQUES, studied by CNES, will carry two key instruments, one for radiative budget and one microwave imager. The orbit will have a low inclination (10 to 15 degree(s)), and the swath 2000 km, allowing repetitive cover of the equatorial band. The altitude will be at least 1000 km, due to microwave imager geometry constraints. The resolution will be relatively coarse, 40 km for the radiative budget instrument, 15 to 100 km for the microwave imager. TROPIQUES will be used in synergy with the polar platforms and geosynchronous satellites of the years 2000. It will provide a useful complementary system for the global study of our climate.