NOVELTY - An initial feedstock comprising unsaturated ester and/or unsaturated acid is provided. The unsaturated ester in initial feedstock is optionally hydrolyzed to form hydrolyzed feedstock. The initial feedstock or hydrolyzed feedstock is optionally transesterified to form transesterified feedstock. The initial feedstock, hydrolyzed feedstock or transesterified feedstock is cross-metathesizied with olefin feedstock (14,33) in presence of metathesis catalyst, to form metathesized product (22) comprising high-weight ester or high-weight acid having hydrocarbon chain lengths of more than 18C.    USE - Method for producing high-weight ester/acid/derivative used for detergent, surfactant, structurant, emollient, adhesive, lubricant, film, paint, paint stripper, coating, plasticizer, resin, binder, solvent, soil stabilization composition, chemical grouting composition, personal care product e.g. lotion, biodiesel composition, crop protection product, oilfield drilling fluid, chemical for oil recovery, and wax composition (all claimed) for cosmetics, pharmaceutical preparation, car polish, shoe polish, floor polish, and manufacture of candle.    ADVANTAGE - The high-weight ester/acid/derivative has excellent thermal oxidative ability, and provides personal care products having favorable sensory properties, and is transported easily.    DETAILED DESCRIPTION - An initial feedstock comprising unsaturated esters and/or unsaturated acids having hydrocarbon chain length of less than or equal to 24C is provided, and the unsaturated esters in the initial feedstock is optionally hydrolyzed to form a hydrolyzed feedstock. The initial feedstock or hydrolyzed feedstock is optionally transesterified to form a transesterified feedstock. The initial feedstock, hydrolyzed feedstock or transesterified feedstock is cross-metathesizied with an olefin feedstock in presence of a metathesis catalyst, to form metathesized product comprising high-weight esters or high-weight acids having hydrocarbon chain lengths of more than 18C. At least a portion of the hydrocarbon chain length in the metathesized product is more than the hydrocarbon chain length in the initial feedstock.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view explaining production of high-weight ester/acid/derivative.    Natural oil (12)    Olefin feedstock (14,33)    Metathesis product (22)    Distillation unit (30)    Olefin (32,74)    High-weight ester/high-weight acid and high-weight derivative (37)    Fatty acid methyl ester (72)