In organic chemistry, thioketenes are organosulfur compounds analogous to ketenes with the general formula , where R is alkyl or aryl.  The parent thioketene (ethenthione) has the formula . It is the simplest thioketene.  Thioketene is stable as a gas, but like most thioketenes, it polymerizes upon condensation.  
Some thioketenes are produced as transient species upon pyrolysis of 1,2,3-thiadiazoles. It has been suggested that thioketene could be involved in cell damage processes.