By converting modified silica aerogels to the corresponding silicon/silicon carbide (Si/SIC) without losing its nanostructure, three-dimensional mesoporous (3DM) Si/SiC composites are successfully synthesized via one-step magnesothermic reduction at relative low temperature (650 degrees C). The phase composition and microstructure of the resulting samples are measured by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), Raman spectra, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). N-2-sorption isotherms results show that the products have high Brunauer-Emmett-Teller (BET) specific surface areas (up to 656 m(2) g(-1)) and narrow pore-size distributions (1.5-30 nm). The composites exhibit a strong photoluminescence (PL) in blue-green light region (peak centered at 533 nm). We have set out work on the biocompatibility and enhancing PL of samples. As a result of excellent performances of the composites, it can be expected to have significant application in optoelectronics, biosensors, biological tracer and so on. Crown Copyright (c) 2013 Published by Elsevier Ltd. All rights reserved.