This Technical Report presents the results of interlaboratory testing for the determination of thermal conductivity and thermal diffusivity of two poly(methyl methacrylate) (PMMA) materials by means of the transient and the modulated methods presented in ISO 22007 parts 2 to 4 [1 - 4] and additional transient and steady state methods. The instructions for the intercomparison are presented in Annex A with key items reproduced in the main part of this Technical Report. The detailed results of individual laboratories are presented in Annexes B to F.