This work is a continuation of our studies on experimental measurements of physical properties on binary mixtures of the ionic liquid (IL) family 1-alkyl-3-methyl imidazolium tetrafluoroborate (CnMIM-BF4) with water and ethanol. Here, we present density for the ternary system Butyl-MIM-BF4 + ethanol + water at two temperatures (298.15K and 323.15 K) and seven pressures (from 0.1 to 30 MPa). It should be noted that BMIM-BF4 is the only IL of the family CnMIM-BF4 that can be mixed with water and ethanol in all range of concentrations at room conditions. From the density data measured in function of pressure and temperature other important derived thermodynamic properties can be calculated, such us excess molar volumes, isothermal compressibility, isobaric expansion and the thermal pressure coefficients. These properties for selected ternary mixtures will be discussed and compared with data from the scarce number of published results for similar ternary mixtures with this same IL (c) 2010 Elsevier B.V. All rights reserved.