Thiocholine bromide was proposed as a cationic capping ligand for a variety of metal and semiconductor nanoparticles with a good dispersibility in an ionic liquid (IL). The stability of NPs was improved in the IL compared to that in water, which was verified by an improved emission property of semiconductor nanoparticles and higher thermal stability of gold nanoparticles. The cationic thiocholine was further demonstrated as a surface ligand for CdTe nanoparticle dispersible in organic media in combination with various anions.