A high dispersion, multi-channel visible spectrometer has been developed for the ISTTOK tokamak, aiming at measuring the evolution of both the ion temperature and the plasma poloidal velocity, by analysis of a CIII spectral line, during the low density (5x1018 m-3), low electron temperature (160 eV) and short duration (40 ms) ISTTOK plasmas. High spectral dispersion was obtained using a double monochromator configuration with two high ruling density (2700 l/mm), non-uniform groove spacing and 1-m focal length concave diffraction gratings mounted near the Rowland circle. The dispersed radiation is focussed onto a commercial double micro-channel plate in a V-stack assembly image intensifier. The input quartz window is followed by a S20 photocathode while the micro-channel output is proximity focussed on a P46 phosphor screen. The light collection is performed by a fast (f#=1) relay lens built with two high diameter condensers in a back-to-back configuration. A 2048-element Photodiode CCD optical multi-channel analyser is placed at the lens focal plane to record the plasma radiation spectral profile. Laboratory tests have shown that a high dispersion has been achieved (about 1.65 Å /mm), while keeping good temporal resolution (5 ms). Rather precise peripheral ion temperatures and plasma poloidal velocity have been obtained from respectively the Doppler broadening and Doppler shift of the CIII spectral line at 465 nm (33D® 33P). Typical values measured for these parameters were Ti@ 25 eV and vq @ 6 km/s. This latter result is in good agreement with that obtained from a set of Langmuir probes. The measured poloidal velocity corresponds, at the limiter radius (r=8.5 cm), to a rotation frequency of about 11.5 kHz. At this frequency strong peaks are observed in the spectral analysis of both the main plasma parameters and the Mirnov coils signals (fundamental tearing mode).