Ethylene (E), propylene (P), and 1-pentene (A) terpolymers differing in monomer composition ratio were produced, using the metallocenes rac-ethylene bis(indenyl) zirconium dichloride/methylaluminoxane (rac-Et(Ind)(2)ZrCl2/MAO), isopropyl bis(cyclopentadienyl)fluorenyl zirconium dichloride/methylaluminoxane (Me2C(Cp)(Flu)ZrCl2/MAO, and bis(cyclopentadienyl)zirconium dichloride, supported on silica impregnated with MAO (CP2ZrCl2/MAO/SiO2/MAO) as catalytic systems. The catalytic activities at 25 degrees C and normal pressure were compared. The best result was obtained with the first catalyst. A detailed study of C-13 NMR chemical shifts, triad sequences distributions, monomer-average sequence lengths, and reactivity ratios for the terpolymers is presented. (C) 2007 Wiley Periodicals, Inc.