Solyak, N. Awida, M.H. Grassellino, A. Grimm, C.J. Hocker, A. Holzbauer, J.P. Khabiboulline, T.N. Melnychuk, O.S. Rowe, A.M. Sekutowicz, J.K. Sergatskov, D.A. Solyak, N. JACoW Geneva, Switzerland 978-3-95450-178-6 10.18429/JACoW-SRF2015-THPB089 English 1349-1353 THPB089 HOM cavity operation coupling higher-order-mode Contribution to a conference proceedings 2015 2015-12 http://dx.doi.org/10.18429/JACoW-SRF2015-THPB089 http://srf2015.vrws.de/papers/thpb089.pdf Power dissipation in HOM coupler antenna can limit cavity gradient in cw operation. XFEL design of HOM coupler, feedthrough and thermal connection to 2K pipe was accepted for LCLS-II cavity based on simulation results. Recently a series of vertical and horizontal tests was done to prove design for cw operation. In vertical test was found no effect of HOM coupler heating on high-Q cavity performance. In horizontal cryostat HOM coupler was tested up-to 23MV/m in continuous wave mode. Result proves that XFEL HOM coupler meets LCLS-II specifications.