Two types of trishomocubanones, pentacyclo[5.4.0.02,6.03,10.04,8]undecan-11-ones and pentacyclo[5.4.0.2,60.3,10O.5,8]undecan-9-ones are catalytically cycloreverted by [Rh(CO)2Cl]2 in different cleavage modes. The mechanism is discussed on the basis of a kinetic study.