Ethylene and 10-undecen-1-ol copolymers, prepared using a nickel complex as catalyst, were studied using differential scanning calorimetry (DSC), X-ray diffraction, and dielectric relaxation spectroscopy. The behavior exhibited by copolymers containing incorporated 10-undecen-1-ol amounts within 0.5 and 4.6 mol % was compared with neat polyethylene. DSC revealed that a new crystalline region with lower thickness lamellae emerges in copolymers due to the side-chains crystallization. Nevertheless, the global crystallization degree decreases due to the loss of crystallinity that occurs in a greater extent in PE-like regions. Dielectric relaxation spectroscopy detected two processes, a low activation energy process below -20 degrees C related with localized mobility increasing in intensity and deviating to higher temperatures with the increase in 10-undecen-1-ol amount, and a high activation energy process ascribed to the glass transition, located at higher temperatures for the different copolymers relatively to neat polyethylene. (c) 2007 Wiley Periodicals, Inc.