A method of making a bijel includes dispersing surface-active nanoparticles in a ternary liquid mixture. The ternary liquid mixture includes a hydrophilic liquid, a hydrophobic liquid, and a solvent. The ternary liquid mixture is contacted with water. A bijel includes a stable mixture of two immiscible liquids separated by an interfacial layer of colloidal particles. The bijel has temperature-independent stability, and the domain sizes are below one micrometer.