Carbon-silica composites with mesoporous structures were synthesized from low-cost materials by conventional heating. The carbon source used was vinasse, a by-product of ethanol production from molasses, while Na2SiO3 and K2SiO3 were utilized as low cost and abundantly available silica sources as alternatives to tetraethyl orthosilicate (TEOS). The simple preparation method was adopted as follows: vinasse was dehydrated with 50% H2SO4 (1:2 in weight ratio) to produce carbon, after which the silica source was added with weight ratio of vinasse:silica source 0.8:1, 0.2:1 and 0.5:1 for Na2SiO3, K2SiO3 and TEOS, respectively. The mixture was stirred and heated at 80 °C for 6 h, washed with water, and dried at 120 °C for 3 h to obtain the carbon-silica composites. Composites were characterized by N2 adsorption-desorption, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), moisture content, ash content, slurry pH, point of zero charge (pHPZC) and bulk density. The composites exhibited BET (Brunauer–Emmett–Teller) surface areas of 443, 354 and 570 m2/g and average pore diameters of 5.20, 5.52 and 7.63 nm when using Na2SiO3, K2SiO3 and TEOS, respectively, as silica sources. The carbon-silica composites were highly mesoporous, accounting for around 71-80% of the total volume. FTIR analysis showed the presence of Si–O–Si bond for all composites. According to TGA results, the adsorbents were thermally stable up to 700 °C. The slurry pH and pHPZC of each composite was very similar with acidic character (slurry pH 2.63–6.80 and pHPZC 2.95–7.00). The bulk density of composites was 560–660 kg/m3, higher than some commercial activated carbons. These results indicated that the mesoporous carbon-silica composites prepared from vinasse and low-cost silica sources were promising functional materials for use as potential adsorbents.