This study aims to evaluate the antioxidant activity (DPPH radical scavenging assay, Nitric oxide scavenging assay (NO assay), Superoxide radical scavenging assay) of seaweeds available in selected regions of Kerala coast. Four seaweeds of the class Chlorophyceae viz., Chaetomorpha antennina, Chaetomorpha area, Ulva lactuca and Valoniopsis pachynema weres elected for the present work. The algal extracts were prepared in methanol for doing these assays. The antioxidant property was analyzed as percentage of inhibition. It was found that Ulval actuca showed highest radical scavenging activity in DPPH assayand also in NO scavenging assay.Chaetomorpha antennina exhibited lower percentage of inhibitionin all the three assayscompared to the other three algal samples.