Proteins derived from the macroalgal species Palmaria palmata have emerged as potential substrates for the generation of bioactive peptides. The aim of this study was to fractionate, identify and characterize antioxidant peptides from a P. palmata protein hydrolysate. The P. palmata protein hydrolysate generated with the food grade proteolytic enzyme Corolase PP was sequentially fractionated using solid phase extraction and semi preparative (SP) RP-HPLC. The most active SP-RP-HPLC peptide fraction (SP-RP-HPLC-30-F26) was analysed by ESI-MS/MS. Seventeen novel peptide sequences were identified in this fraction. Of the peptides selected for synthesis, Ser-Asp-Ile-Thr-Arg-Pro-Gly-Gly-Asn-Met, showed the highest oxygen radical absorbance capacity (ORAC) and ferric reducing antioxidant power (FRAP) activity with values of 152.43 +/- 2.73 and 21.23 +/- 0.90 nmol TE/mu mol peptide, respectively. The results presented herein indicate that P. palmata derived peptides may have potential applications as health enhancing ingredients and as food preservatives due to their antioxidant activity.