CRISPR/Cas system is a RNA-mediated adaptive prokaryotic immune system against mobile genetic elements. Among three types of CRISPR/Cas system, type I system is related with retraction of double-stranded DNA of a foreign nucleic acid. In this system, Cascade (CRISPR-associated complex for antiviral defense) recognizes the exogenous DNA using the CRISPR RNA and unwinds the double-stranded DNA, resulting in a RNA-mediated loop structure which is cleaved by Cas3 helicase-nuclease. Type I-B Cascade is composed of Csh1, Csh2, Cas4, and Cas5. Since structural and functional information on this Cascade system is missing, its structure-based studies are overtaken using genes originated from the thermostable Thermobaculum terrenum. Among four genes that were cloned and expressed in Escherichia coli, the preliminary structural study on the Csh2 gene is reported here. The gene encoding for Csh2 protein that was recombined with a bacterial expression vector was over-expressed in E. coli and the recombinant protein was purified by sequential chromatographic steps. The purified protein was concentrated and successfully crystallized using the precipitant solution composed of 10 %(w/v) polyethylene glycol 3350, 2% tacsimate at pH 5.0, and 100 mM sodium citrate tribasic dihydrate at pH 5.6. Diffraction data were collected to 1.93 A resolution using synchrotron radiation. The crystal belongs to the primitive triclinic space group P2, with unit cell dimensions of a=53.80A, b=30.39A, c=93.88 A, ?=?=90º, and ?=106.69º. With one molecule in the asymmetric unit, the crystal volume per unit protein weight corresponds with 2.03 A3Da-1 and contains 36% solvent. Since no similar structure, based on the amino sequence similarity, is reported, the structural determination of Csh2 from T. terrenum is being processed using heavy metal ions such as selenium as an anomalous scatterer.