N-Acetyl-D-glucosamine 2-epimerase (GlcNAc 2-epimerase) is one of the key enzymes used in the industrial production of sialic acid (N-acetyl-D-neuraminic acid). It catalyzes the inter-conversion of N-acetyl-D-glucosamine (GlcNAc) to form N-acetyl-D-mannosamine (ManNAc), which can interact with pyruvate to form sialic acid. For application in sialic acid synthesis, the gene of GlcNAc 2-epimerase from Synechocystis sp. PCC 6803 was amplified using the PCR method and cloned to obtain Escherichia coli BL21 with a glutathione S-transterase (GST) tag in the N-terminus. By means of affinity tag, the fusion protein could be purified to homogeneity using a GST resin column and immobilized on particles bound with glutathione (GSH). The overexpressed protein in either tagged or non-tagged form was enzymatic active and able to catalyze the production of ManNAc from GlcNAc. With ManNAc used as the substrate, the purified fusion protein showed a K-m value of 8.9 mM, which is close to the values previously reported in the literature for GlcNAc 2-epimerase, suggesting that the addition of the GST tag could marginally change the affinity of this enzyme for the substrate. The optimal pH for attaining the highest enzyme activity with the GST tagged fusion protein was determined to be 8.0. When the enzymatic activity was estimated at pH 7, the optimal temperature was 50 degrees C.