The adsorption of propylene on copper(II)-exchanged zeolite Y was studied by temperature programmed desorption (TPD) technique and electron spin resonance. The amount of propylene adsorbed increased with increasing copper ion content. Four TPD peaks with desorption temperature maxima at $108^{circ}C({alpha})$, $243^{circ}C({eta})$, $284^{circ}C({gamma})$ and $420^{circ}C({delta})$ were observed (heating rate: $6.4^{circ}C$/min). ${alpha}$Peak which was also observed in the TPD of propylene from NaY may be assigned to propylene physically adsorbed on the zeolite surface, ${eta}$ and ${gamma}$ peaks to the chemisorbed propylene either on copper ion or Bronsted acid site produced by copper ion, and $delta$ peak to cracking products from the polymeric material formed from propylene adsorbed