Abstract: Despite the increasing number of papers about the study of the properties of the ionic liquids (ILs), the knowledge of their ecotoxicity and biodegradability are not still well established. In this work the effect of the addition of five different concentrations of aqueous solutions (10%, 1%, 0.1%, 0.01% and 0% (control) in weight) of the IL [C3C1im][NTf2] on the seed germination of six species of pine and on the microbial activity of a soil under P. radiata was determined. This IL was selected taking into account that his thermophysical properties make it a good candidate to being used as lubricant. Seed germination test of species of Eucalyptus globulus, Pinus halepensis, Pinus nigra, Pinus pinaster, Pinus sylvestris and Pinus radiata were carried out. The reason to select these species was their wide geographical distribution and their great economic, social and ecological interest. Five replies with 25 seeds per Petri dish were incubated for every species and treatments, in total 3750 seeds were incubated (6 species x 5 treatments x 5 replicates x .25 seeds) Germinated seeds were monitoring every Monday, Wednesday and Friday. Germination had been completed in all the species 45 days of incubation. On the other hand, calorimetric experiments were performed using a microcalorimeter 2277 Thermal Activity Monitor (TAM) Thermometric AB. Measurements were carried out in hermetically sealed 5 ml stainless steel ampoules. Soil samples of 1 g size at water-holding capacity were treated with 0.2 ml of aqueous glucose solution to activate the microbial metabolism.Additionally, a comparison between the effects of this IL in the seed germination and soil microbial activity and the corresponding to two well-known salts, sodium chloride and potassium nitrate, in the same conditions was stablished.Acknowledgements: This study was financed by the project EM2013/031 (Xunta de Galicia, Spain)