[en] The octanol/ water partition coefficient (P_o_w) and water solubility (S_w) are important physico-chemical properties for an environmental risk assessment of a chemical substance, as well as ecotoxicity. It can be an indication of the extent to which the chemical might bioaccumulate in aquatic organisms. The log P_o_w of palm-based fatty acids was estimated using high performance liquid chromatography (HPLC) method, while the S_w value was determined using linear correlation between S_w and log P_o_w of reference compounds. The ecotoxicity of palm-based fatty acids was measured using test method OECD 203, Fish Acute Toxicity with common carp (Cyprinos carpio) as the test species. The short-chained C6 to C10 palm fatty acids were chosen for this study because they are generally toxic and can cause irritation to human and may have an adverse effect towards aquatic organisms. The log P_o_w values showed that both C6 and C8 fatty acids had low affinity towards aquatic organisms, but C10 fatty acid showed medium affinity towards these organisms. As for water solubility, C6 fatty acid had high affinity towards water, while both C8 and C10 fatty acids showed medium affinity towards water. The LC_5_0 value of C6, C8 and C10 palm FAs are 7 mg litre"-"1, 7 mg litre"-"1 and 20 mg litre"-"1, respectively. It can be concluded that, the higher the carbon chain number of the fatty acid, the higher is the partition coefficient value, the water solubility decreases. The palm-based fatty acid can be considered as moderately toxic to aquatic organisms. These data can be used by the palm-based oleochemical manufacturers for product registration, preparation of product dossier or for marketing purposes. (author)