Hydroformylation of propene to isobutyraldehyde and n-butyraldehyde was studied in the kinetic regime in a semibatch stainless steel reactor at 85-115 degrees C and 115 bar pressure in 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate solvent with rhodium catalyst cyclohexyl diphenylphosphine as a ligand, which showed lower normal/isometric aldehyde ratio (n/i) than previously studied triphenylphosphine. The rate was pressure and Rh concentration dependent. The regioselectivity was conversion independent; however, dependent on the ligand concentration, as higher ligand concentration promoted isobutyraldehyde formation. The influence of ligand concentration on regioselectivity was investigated. A kinetic model was proposed based on the mechanism of alkene hydroformylation and compared with experimental observations. Numerical data fitting was performed showing good agreement of reaction rates and regioselectivity with experimental data. (C) 2011 American Institute of Chemical Engineers AIChE J, 2012