In this work, we report the growth of carbon nanotubes (CNTs) at temperatures as low as 150 degrees C on an iron oxide-graphene, multicomponent, nano-structural system. A radio-frequency generator and an electrical furnace are separately used to heat the decorated graphene samples in an argon/hydrogen environment without adding any external hydrocarbon source. Few-layer graphene sheets are decorated with iron oxide nanoparticles using a simple one-step process and thoroughly characterized by electron microscopy. The synthesis temperature is varied between 150 and 500 degrees C, and nanotube's presence is confirmed by transmission and scanning electron microscopy. We find that, while the graphene decorated with 5 nm iron oxide nanoparticles forms nanotubes at the lowest temperature (150 degrees C), the decorated samples with larger nanoparticles (15 nm) only initiate nanotube growth at 400 degrees C or higher, indicating a strong size-dependence on the catalytic activity of these nanoparticles. This low-temperature, facile technique opens the door to a wide range of applications for these novel nanoparticle/graphene-nanotube systems in areas varying from nano-electronics and energy harvesting to bio-nano. (C) 2012 Elsevier Inc. All rights reserved.