Abstract: A catalytically active filter for use in hot gas filtration to simultaneously remove solid particles and one or more undesirable compounds from a hot gas stream is partly or fully impregnated with a suitable catalyst. The compounds are selected from HCN, arsenic, organic sulfur compounds and carbonyls. The filter is prepared by making an impregnation liquid, which comprises a catalytically effective amount of at least one active metal and an oxide support, impregnating the filter substrate with the impregnation liquid by dipping it in the liquid or spraying it with the liquid to control the amount of liquid and drying and optionally calcining the impregnated filter.