Considerable attention has been devoted to studying the tanning properties of certain organic compounds known as aldehydes. A number of new aldehydes, especially dialdehydes, had become available, but no information existed about their tanning ability. Research demonstrated the versatile tanning properties of one of these dialdehydes, glutaraldehyde, and the desirable properties it imparts to leather. This, couples with its commercial availability at reasonable cost, soon led to its commercial use in tanning by the leather industry in the U.S. This article discusses research results regarding this material.