Metal–organic charge transfer complex (MOCT) material have good application potentials. We report a high carrier mobility in MOCT material Cu:tetracyanoquinodimethane (Cu:TCNQ) single nanowire (NW). A novel floating back-gate field effect transistors is fabricated using Cu:TCNQ single NW of diameter ranging from ∼50 to 100 nm and length ∼1.0–2.0 μm as channel material. Floating gate is made of conducting Si (c-Si) electrically isolated from the environment by thermally grown SiO2 (100 nm thickness) all around it, which is an easy and inexpensive approach to reduce leakage current and improve the device performance. The devices can exhibit on/off current ratio of ∼102–104 at room temperature. Mobility of the NW channel as measured in different single NW devices is ∼4.3 × 102 to 1.2 × 104 cm2 V–1 s–1 which is the best reported mobility in such molecular materials. The observed high mobility has been proposed to arise from π–π stacking of the molecular orbitals of donor–acceptor type CT materials and good crystallinity and also small device size that reduces carrier scattering.