  We present the compilation and properties of a Meta-Catalogue of X-ray
detected Clusters of galaxies, the MCXC. This very large catalogue is based on
publicly available ROSAT All Sky Survey-based (NORAS, REFLEX, BCS, SGP, NEP,
MACS, and CIZA) and serendipitous (160SD, 400SD, SHARC, WARPS, and EMSS)
cluster catalogues. Data have been systematically homogenised to an overdensity
of 500, and duplicate entries originating from overlaps between the survey
areas of the individual input catalogues are carefully handled. The MCXC
comprises 1743 clusters with virtually no duplicate entries. For each cluster
the MCXC provides: three identifiers, a redshift, coordinates, membership of
original catalogue, and standardised 0.1-2.4 keV band luminosity L_500, total
mass M_500, and radius R_500. The meta-catalogue additionally furnishes
information on overlaps between the input catalogues and the luminosity ratios
when measurements from different surveys are available, and also gives notes on
individual objects. The MCXC is available in electronic format for maximum
usefulness in X-ray, SZ, and multi-wavelength studies.
