Abstract: A catalytic oxidation unit of the type used for oxidizing fumes from ovens and the like comprises a metallic housing providing a tubular body portion with spaced shoulders in the through passage and a block of cellular ceramic material therebetween. One of the spaced shoulders is provided by an apertured front wall on the housing, and the block of ceramic material is biased against this front wall shoulder by resiliently compressible means acting between the block and the other shoulder. The ceramic material block has an oxidation catalyst on the walls of the cells thereof which is effective to oxidize organic materials in the fumes passing through the metallic housing and the block of ceramic material therewithin.