Periodic open cellular structures (POCS) are becoming increasingly popular as catalyst carriers due to favorable properties: mixing flow, intense heat/mass transfer and low flow resistance. Their design and manufacturing are relatively easy and cheap. The presented paper focuses on the characterization of POCS in relation to their definition, types, classification and properties. Next, the design and manufacturing methods are described. Finally, the literature review dealing with the application of POCS in catalytic processes are presented.