We have determined the electron–phonon interaction in type II Dirac semimetallic 1T-PdTe 2 by means of helium atom scattering. While 1T-PdTe 2 is isostructural with 1T-PtTe 2, only the former is superconductor. The difference can be traced to the substantially larger value of the electron–phonon coupling in 1T-PdTe 2, λ= 0.58, obtained from the Debye-Waller attenuation of the He specular peak. With this value and the surface Debye temperature, Θ D= 106.2 K, we have figured out the superconducting critical temperature, T c= 1.83 K given by the BCS theory, which is in good agreement with T c=(1.95±0.03) K obtained with low-temperature scanning tunneling microscopy. The value of the effective mass related to Θ D indicates that the large electron–phonon coupling in 1T-PdTe 2 is due to coupling, not only with the zone-center optical mode O 2 at 9.2 meV, as proposed in a recent theoretical study, but also with …