Abstract: Both compound Ⅰ and Ⅱ are intermediates in fluocinanide acetate synthesis. Ⅰ could be dehydrogenated to Ⅱ in 62%～63% yields by Arthrobactor simplex No. A-l, which was selected in our laboratory. When concentration of Ⅰ was 0.1%, it was transformed so fast that Ⅱ could not be accumulated. When concentraction was increased to 0.2%,four intermediates Ⅳ,Ⅴ,Ⅵ and Ⅶ were formed in addition to a little amount of product Ⅱ.When concentration of substrate Ⅰ was increased to 0.5% and B-CS buffer solution and 4% alcohol (95%, Ⅴ/Ⅴ) were added, compound Ⅱ in cuboidal microcrystalline form was obtained. Under this condition, the yield was steady and melting point was above 250℃.