BACKGROUND Catalytic formation of lactic acid from biomass glycerol is a sustainable alternative to the conventional fermentation process starting from carbohydrate and the chemical route using HCN and acetaldehyde. Highly concentrated glycerol can be effectively converted to lactic acid using hydroxyapatite-supported palladium particles in the presence of NaOH. RESULTS The 3% hydroxyapatite-supported palladium catalyst (Pd-3/HAP) demonstrates excellent activity (TOF = 1274 h(-1) for a batch time of 90 min) with a high selectivity (95%) towards lactic acid at 99% glycerol conversion (230 degrees C, NaOH:glycerol molar ratio = 1.1, and glycerol/total Pd intake = 1926). Under the same reaction conditions, the selectivities of lactic acid were 82% and 90% on Pd-0.75/HAP and Pd-1.5/HAP catalysts, respectively. The Pd-3/HAP catalyst was recycled five times in a batch set-up without a significant drop in activity and lactic acid selectivity, which is indicative of good catalyst stability. CONCLUSIONS Pd-based catalysts on available hydroxyapatite supports are efficient catalysts for glycerol selective oxidation. The catalysts possess active PdO and Pd-0 species well dispersed on the functionalized hydroxyapatite support. Pd-0 nanoparticles and NaOH synergistically catalyze the reaction process. (c) 2018 Society of Chemical Industry