Abstract: A program LYCT which can generate an exhaustive, nonredundant list of all the acyclic structural isomers of a given empirical formula has been completed. It can also prune these isomers by means of feeding the program with “BADLIST” and “GOODLIST”. The numbers of isomers of some compounds resulted from LYCT are however, inconsistent with previous data^[1.9], The differences are discussed to demonstrate the validity of this program. An example illustrating the use of LYCT is presented.