Based on a simple low-temperature chemical solution method, multiwalled carbon nanotubes (MWCNTs) are coated discontinuously with a alumina gate-dielectric shell (see Figure) and application as p-type field-effect transistors is demonstrated. With a coating thickness of 8 nm, the drain current exceeds the gate current by a factor of 10(4)-10(5), confirming the excellent gate insulation provided by the alumina dielectric.