Abstract Polyaniline (PANI)/para-toluene sulfonic acid (pTSA) and PANI/pTSA-TiO 2 composites were prepared using chemical method and characterized by infrared spectroscopy (IR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM). The electrical conductivity and magnetic properties were also measured. In corroboration with XRD, the micrographs of SEM indicated the homogeneous dispersion of TiO 2 nanoparticles in bulk PANI/pTSA matrix. Conductivity of the PANI/pTSA-TiO 2 was higher than the PANI/pTSA, and the maximum conductivity obtained was 9.48 (S/cm) at 5 wt% of TiO 2. Using SQUID magnetometer, it was found that PANI/pTSA was either paramagnetic or weakly ferromagnetic from 300 K down to 5 K with H C ≈ 30 Oe and M r ≈ 0.015 emu/g. On the other hand, PANI/pTSA-TiO 2 was diamagnetic from 300 K down to about 50 K and below which it was weakly ferromagnetic. Furthermore, a nearly temperature-independent magnetization was observed in both the cases down to 50 K and below which the magnetization increased rapidly (a Curie like susceptibility was observed). The Pauli susceptibility ( χ pauli) was calculated to be about 4.8 × 10 −5 and 1.6 × 10 −5 emu g −1 Oe −1 K for PANI/pTSA and PANI/pTSA-TiO 2, respectively. The details of these investigations are presented and discussed in this paper.