Poly(2-hexadecyloxyaniline)/selenium (Se) nanocomposite monolayer was successfully prepared by spreading 2-hexadecyloxyaniline (2-C(16)OAn) on selenious acid aqueous solution without additional oxidant and reductant. The formation of Se nanoparticles and the polymerization of 2-C(16)OAn in the monolayer occurred simultaneously. The results showed that the limiting area per repeat unit on selenious acid subphase was larger than that on pure water, which indicated the formation of poly(2-hexadecyloxyaniline)/Se nanocomposite monolayer at air/water interface. The amorphous spherical Se nanoparticles and triangular single-crystal ones in the Langmuir-Blogett (LB) films were formed at 20 +/- 1 degrees C and 35 +/- 1 degrees C, respectively. Poly(2-hexadecyloxyaniline)/Se nanocomposite LB films with excellent quality could be obtained on different substrates, indicating that the transfer ratio of monolayer was close to unity. Furthermore, poly(2-hexadecyloxyaniline)/Se nanocomposite LB films possessed high conductivity with the current of 10(-5) A cm(-1). (C) 2010 Elsevier B.V. All rights reserved.