Abstract : The present study is focused on the comparison of structural and optical properties of nanocomposite of Fe2O3 formed with both rice straw, a biopolymer and polyindole, a conducting polymer. For comparison, counter parts were also synthesized. Nanoparticles of iron oxide were synthesized through controlled co-precipitation method in presence of citric acid. Structural characterizations of all the synthesized samples were carried out using XRD. Comparison of XRD of metal oxide with JCPDS confirmed that the formed metal oxide was Fe2O3. Optical studies of all the samples were carried out using UV/Vis spectroscopy. From band gap calculation it was seen that all of them except polyindole showed subgaps. Also these samples were employed as photocatalyst in the photocatalytic degration study of organic acidic dye Congo Red. Results suggested that the nanocomposites prepared in the present study are promising photocatalysts. Also an increase in degradation efficiency was observed in the case of nanocomposites when compared to their counterparts. © Published under licence by IOP Publishing Ltd.