The present invention relates to a catalyst for preparation of chlorine by catalytic gas phase oxidation of hydrogen chloride with oxygen, in which the catalyst comprises at least tin dioxide as a support material and at least one ruthenium-containing compound as a catalytically active material, and comprises, as an additional secondary constituent, a compound of an element or an element selected from the group of: Nb, V, Ta, Cr, Mo, Au, In, Sc, Y and lanthanoids, especially La and Ce.