A boron-doped carbon nanotube (BCNT)-modified glassy carbon (GC) electrode was constructed for the detection of L-cysteine (L-CySH). The electrochemical behavior of BCNTs in response to L-cysteine oxidation was investigated. The response current of L-CySH oxidation at the BCNT/GC electrode was obviously higher than that at the bare GC electrode or the CNT/GC electrode. This finding may be ascribed to the excellent electrochemical properties of the BCNT/GC electrode. Moreover, on the basis of this finding, a determination of L-CySH at the BCNT/GC electrode was carried out. The effects of pH, scan rate and interferents on the response of L-CySH oxidation were investigated. Under the optimum experimental conditions, the detection response for L-CySH on the BCNT/GC electrode was fast (within 7 s). It was found to be linear from 7.8 x 10(-7) to 2 x 10(-4) M (r=0.998), with a high sensitivity of 25.3 +/- 1.2 nA mM(-1) and a low detection limit of 0.26 +/- 0.01 mu M. The BCNT/GC electrode exhibited high stability and good resistance against interference by other oxidizable amino acids (tryptophan and tyrosine). (C) 2008 Elsevier Ltd. All rights reserved.