Selectively catalytic oxidation of 1,2-propanediol with O-2 to lactic, formic, acetic acids over Ag nanopartides was investigated. Ag nanoparticles and alkali cocatalyzed the oxidation of 1,2-propanediol. The Ag nanoparticles with the average particle sizes of 15.2-43.2 nm were prepared by using citric acid (CA), sodium dodecylbenzenesulfonate, tween-80 (Tween), D-sorbitol, and polyvinylpyrrolidone as organic modifiers. When the oxidation of 1,2-propanediol was catalyzed by Ag-rween nanoparticles at 120 degrees C for 4 h in NaOH solution, the lactic acid selectivity was 62% at the 1,2-propanediol conversion of 65.6% while over Agcf, nanoparticles, the acetic and formic acids selectivities were 63.2% and 30.5%, respectively, at the complete conversion of 1,2-propanediol. The small-sized Ag nanoparticles favored the formation of acetic and formic acids while the Ag nanoparticles with the average particle sizes of 19.4-25.3 nm favored the formation of lactic acid. The Ag nanoparticle sizes also affected the kinetics for the catalytic oxidation of 1,2-propanediol. (C) 2015 Elsevier Inc. All rights reserved.