A new
SI unit, measuring
catalytic activity. Its symbol is
kat and it is equal to one
mole per second. From it is derived a unit of
catalytic concentration, the katal per metre cubed.
It had been in practical use for thirty years, as had various other unofficial units. The SI stepped in and adopted it at their 21st CGPM (General Conference) in October 1999. Normally they're chary of adopting new units but they do it when it affects human health and safety, and the katal is especially needed in biochemistry.