INTRODUCTION This Item presents values of thermal conductivity at saturation pressure@ in tabular form@ for the liquid heterocyclic nitrogen compounds. The data on which these recommended values of thermal conductivity are based are the most reliable available and the range covered is from the melting point to approximately 0.9 of the critical temperature. Quantities are expressed in SI Units but conversion factors to other units are provided in Section 3. Section 4 describes the procedure used to obtain the values of thermal conductivity presented and indicates the effect of pressure. Section 5 gives an explanation of the Tables and indicates the uncertainties in the values presented in them. In Section 6@ References 1 to 6 are sources of supplementary reading matter. Reference 6 is a useful summary and contains the older sources of data used in the preparation of this Data Item; a more recent source of data is given as Derivation 7.