The effect of carbon black and ceramic (alpha -Al2O3 and gamma -Al2O3) particles on the cationic and polymer chain mobility have been investigated in poly(ethylene oxide)-lithium salt (LiClO4 and LiBF4) solid composite polymer electrolytes by using nuclear magnetic resonance (NMR) techniques. Proton (H-1) and lithium (Li-7) lineshapes and spin-lattice relaxation times were measured as a function of temperature. The Li-7 data indicates that the lineshape and relaxation is affected by the coupling of its quadrupolar moment to the surrounding electric field gradients. Activation energies xtracted from the Li-7 relaxation data are in the range 0.20-0.25 eV. Results show that the addition of alpha -Al2O3 influenced both, the relative cation mobility and the polymer chain motion. Calculation shows that this result is in quantitative agreement with the conductivity data.