The molecular weight of polyacrylic acid (PAA) was determined by a viscometric method using NaNO3 as solvent at 30degreesC. The specific electric conductivities (sigma) of PAA as well as PAA doped with carbon black (CB), chromium oxide (Cr2O3), and cupferron with different concentrations (from 0.25 to 1 wt %) were measured at a temperature range 360-400 K. IR spectra of some polymers were determined and it was shown that when PAA was doped with 0.5 wt % CB, a C-O-C band appeared at 775-875 cm(-1). The positron annihilation lifetime (PAL) spectra in PAA doped with the above-mentioned dopants were measured as a function of their concentrations. It was observed that the short lifetime intensity I-1 decreased, whereas the intermediate lifetime intensity I-2, which is related to the conductivity of the material, increased with increasing the wt % of Cr2O3 and cupferron as well as at low concentrations of CB. These results are discussed in terms of the conducting island model. It was found that there were distinct positive relationships between sigma and I-2.