Compare viscometry measurements as a function of temperature were made on two lyotropic nematic calamitic. liquid crystals involving the potassium laurate/decanol/water and potassium laurate/potassium chloride/water systems. It was observed that whereas, at nematic calamitic phase (system with decanol), the viscosity measurements are smaller than those nematic calamitic phases (systems with potassium chloride). The results are discussed and compared to other liquid crystal sytems.