The thermal conductivities of 1-butyl-3-methylimidazolium L-tryptophan ([BMIM][L-trp]), water, ethanol, [BMIM][L-trp] + water, [BMINI][L-trp] + ethanol, water + ethanol, and [BMIM][L-trp] + water + ethanol were investigated from 283.15 to 333.15 K covering the whole scale of concentration at atmospheric pressure with the transient hot wire method. The thermal conductivities of pure [BMIM][L-trp] decease linearly from 0.180 to 0.177 W.m(-1).K-1 with increasing temperature. The uncertainty of the measurement was less than 2% at the 0.95 confidence level. The experimental data of binary and ternary mixtures were correlated by a second-order Scheffe polynomial as a function of composition and temperature. The average relative deviation of the calculated values with experimental data was 0.58%.