3C-SiC nanowires and nanocones were grown by pyrolysing mixture of acid-treated oil palm empty fruit bunch fibres and rice husk ash (RHA), which acted as carbon and silicon source, respectively. The effects of different RHA amounts and pyrolysis temperature were studied. When the amount of RHA was increased to 80 % of the mixture, there was a change in the morphology from nanowires to nanocones. Overall, it was found that 40 % of RHA in the mixture was the ideal amount in growing the nanowires with the maximum yield and with the least amount of impurities. When the pyrolysis temperature was raised, there was an increase in the amount, diameter and length of the nanowires. The proposed main growth mechanism for the SiC nanowires were combination of solid-state reaction and vapour-solid mechanisms, with some nanowires grown under vapour-liquid-solid (VLS) mechanism induced by trace metals as well. The growth of the nanocones could also be related to VLS mechanism.