As nanomaterial possessing moderate conductivity and dielectric property, novel hexanoic acid doped polyaniline (PAni) nanocomposites containing TiO2 nanoparticles were prepared by template free method. Morphology, conductivity, dielectric and microwave absorption properties of PAni nanocomposites were investigated. The resulted nanorods/tubes in SEM images clearly showed that polymerization proceeded in micelle/water interface through elongation. The nanocomposites synthesized at 0 degrees C resulted in large number of nanorods/tubes compared with those synthesized at 25 degrees C. The nanocomposites synthesized at 0 degrees C possess higher permittivity and heterogeneity, hence will give rise to good microwave absorption property (>99.0% power absorption) in the frequency range of 10-13 GHz compared with 25 degrees C. Among all nanocomposites prepared, PAni/HA/TiO2 with highest permittivity, heterogeneity and loss tangent has achieved maximum reflection loss of -31 dB (>99.9% power absorption) at 10 GHz. (c) 2007 Elsevier B.V. All rights reserved.