Malate synthase (EC 4.1.3.2) was induced in Pseudomonas fluorescens grown on malonate as a sole source of carbon. This enzyme was purified by the combined methods of ammonium sulfate fractionation, DEAE-Sephacel ion exchange chromatography, tartronate $omega$-aminohexyl Sepharose 4B affinity chromatography and hydroxyapatite chromatography in an electrophoretically homogeneous form. Molecular size of the enzyme was estimated by Sephadex G-150 gel filtration to be 79,000 dalton composed of single polypeptide. pH optimum of the enzyme was 8.5 and the pI was 4.6. The rate of acetyl group incorporation on variable concentration of substrate into malate was well fitted to a typical Michaelis-Menten kinetics. From the Lineweaver-Burk plot, Km and $V_{max}$ for acetyl-CoA were calculated to be $17.5;{mu}M$ and 21 umoles/min/mg, respectively and those for glyoxylate to be $7.7;{mu}M$ and $35.7;{mu}moles/min/mg$, respectively. The activity of this enzyme was inhibited by glycolate with $16.8;{mu}M$ of Ki, and oxalate with $25;{mu}M$ of Ki, competitively. Some metabolic intermediates such as citrate, isocitrate and succinate, also inhibited the enzyme activity. Iodoacetamide and p-chloromercuriphenylsulfonic acid strongly inhibited the enzyme acitivity, suggesting that there may be a reactive thiol group(s) at or near the active site. The purified malate synthase was immunogenic in rabbit and Ouchterlony double diffusion analysis revealed a single precipitation line with the enzyme.