Simultaneous activation of CO2 and H2O was carried out in a non thermal plasma dielectric barrier discharge reactor operated under ambient conditions. The plasma reactor packed with partially reduced NiO/Al2O3 catalyst showed better CO2 conversion than both the unreduced NiO/Al2O3 and with plasma (no catalyst), whereas, highest syngas selectivity was observed with unreduced NiO/Al2O3. An interesting observation is the formation of carbon nanofibres (CNFs) along with syngas with a reduced NiO catalyst integrated to the plasma, whereas, pure NiO only led to the formation of methane. The reduction of CO2 by in situ formation of hydrogen from water splitting may produce CH4 and plasma-assisted chemical vapour decomposition of CH4 may lead to the formation of CNFs. © 2013 Elsevier Ltd.