Supercritical fluid carbon dioxide (SF-CO(2)) extraction (SFE) of seed oil from yellow horn and its anti-oxidant activity were investigated. The effects of CO(2) flow rate and particle size were firstly optimized, and a central composite design (CCD) combined with response surface methodology was used to study the effects of extraction pressure, temperature and time on the extraction yields. A maximal extraction yield of 61.28% was achieved under optimal conditions of extraction pressure 30 MPa at 45.68 degrees C, 2.08 h and CO(2) flow rate 12 kg/h with 0.5 mm particle size. By analyzing the chemical composition of the seed oil, we found that the content of unsaturated fatty acids was approximately 90%. Furthermore, the anti-oxidant activity of seed oil was assessed by a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay and a beta-carotene bleaching test. Yellow horn seed oil possessed notable concentration-dependent antioxidant activity with IC(50) values of 0.151 and 0.195 g/mL, respectively. (C) 2009 Elsevier Ltd. All rights reserved.