All-sky data from the Planck  survey and the Meta-Catalogue of X-ray detected Clusters of galaxies ( MCXC ) are combined to investigate the relationship between the thermal Sunyaev-Zeldovich ( SZ ) signal and X-ray luminosity . The sample comprises \sim 1600 X-ray clusters with redshifts up to \sim 1 and spans a wide range in X-ray luminosity . The SZ signal is extracted for each object individually , and the statistical significance of the measurement is maximised by averaging the SZ signal in bins of X-ray luminosity , total mass , or redshift . The SZ signal is detected at very high significance over more than two decades in X-ray luminosity ( 10 ^ { 43 } { erg / s } \lesssim L _ { 500 } E ( z ) ^ { -7 / 3 } \lesssim 2 \times 10 ^ { 45 } { erg% / s } ) . The relation between intrinsic SZ signal and X-ray luminosity is investigated and the measured SZ signal is compared to values predicted from X-ray data . Planck  measurements and X-ray based predictions are found to be in excellent agreement over the whole explored luminosity range . No significant deviation from standard evolution of the scaling relations is detected . For the first time the intrinsic scatter in the scaling relation between SZ signal and X-ray luminosity is measured and found to be consistent with the one in the luminosity – mass relation from X-ray studies . There is no evidence of any deficit in SZ signal strength in Planck  data relative to expectations from the X-ray properties of clusters , underlining the robustness and consistency of our overall view of intra-cluster medium properties .