Ionic liquids have proved to be excellent heat transfer fluids and alternatives to common HTFs used in industry for heat exchangers and other heat transfer equipment. However, its industrial utilization depends on the cost/kg of its production, to be competitive for industrial applications with biphenyl and diphenyl oxide, alkylated aromatics, and dimethyl polysiloxane oils, which degrade above 200 degrees C and possess some environmental problems. The efficiency as a heat transfer fluid depends on the fundamental thermophysical properties necessary to model convective heat transfer (density, heat capacity, thermal conductivity, and viscosity) and calculate the heat transfer coefficients in given heat exchangers geometries. l-Ethyl-3- methylimidazolium methanesulfonate [C(2)mim][CH3SO3] (CAS no. 14502245-3) (ECOENG 110) is actually produced by BASF, under the trade name of Basionics ST 35, with an assay >= 97% with <=<0.5% water and <= 2% chloride (Cl-). Density, speed of sound, heat capacity, viscosity, electrical, and thermal conductivity of the industrial product, after drying under vacuum, were obtained for the temperature range 283.15-363.15 K, at atmospheric pressure. Values of the thermal properties studied showed an interesting phase behavior below the melting point (303 K), which suggests the existence of second order-disorder transitions (lambda-type) before reaching the freezing point. A study was carried out to investigate the toxicity of [C(2)mim] [CH3SO3] in saltwater crustaceous. The lethal concentration was determined with Artemia, and the LC50 was found to be higher than with an organic solvent, such as ethylene glycol.