Abstract: The explorations of prodegradant additives for plastics from trans-metals organic salts have been being conducted. This study reports a method of synthesis of manganese carboxylates and their characterization. The new method involves reaction between molten carboxylic acid with sodium hydroxide in alcoholic solution to produce sodium carboxylate and continued by reacting sodium carboxylate with chloride salt of manganese. First reaction and second reaction were conducted at 80-85°C and under perfect agitation. Second reaction took place well in the low concentration of manganese chloride, about 0.25 M or less. Manganese carboxylates (manganese laurate, manganese palmitate, manganese stearate) densities are 0.376, 0.227 and 0.201 g cm-3, respectively. Their onset melting points are 104.95, 111.27 and 114.69°C, respectively, obtained by Differential Scanning Calorimeter (DSC) test. Thermogravimetric Analyzer (TGA) test have been done on manganese carboxylates to investigate their thermal stabilities. The results obtained in this study have exposed the capacity of manganese carboxylates stability at processing temperature of polyethylene. It was also found that manganese carboxylates were insoluble in water, ethanol, acetone, n-hexane, cyclohexane, benzene and toluene.