Black peppercorn, nutmeg, rosehip, cinnamon and oregano leaf were extracted with 50% acetone and 80% methanol, and evaluated for their radical-scavenging activities against radical cation, DPPH radical, peroxyl (ORAC) and hydroxyl radicals. For each extract, total phenolic content (TPC) and chelating activity were also determined. The extracts of all botanical samples showed significant radical-scavenging capacities, TPC and chelating abilities. The 50% acetone extract of cinnamon had the highest A radical cation-scavenging capacity of 1243 micromol TE/g and the greatest ORAC value of 1256 micromol TE/g on a per weight basis. The 50% acetone extracts of black peppercorn and cinnamon showed higher radical cation-scavenging, ORAC, Fe+2 chelating ability and TPC value, but lower DPPH radical value than the corresponding 80% methanol extracts. The 80% methanol extract of nutmeg had greater radical cation, ORAC and TPC values than the 50% acetone extract. Electronic spin resonance (ESR) measurements demonstrated that cinnamon had the strongest hydroxyl radical-scavenging activities among all the tested botanical materials. These data indicate that black peppercorn, nutmeg, rosehip, cinnamon and oregano leaf may serve as potential dietary sources of natural antioxidants for improving human nutrition and health. The extracting solvent may alter the antioxidant activity measurement for selected botanicals, including spices and herbs.