A heat-stable lipase gene was isolated from a local thermophilic bacterium, Bacillus sp. strain L2. The recombinant L2 lipase is highly active over wide temperature and pH ranges of 55 to 80°C and pH 6 to 9, respectively. Pure L2 lipase was optimally crystallized by using counter diffusion method, both. Further studies on different incubation temperatures showed that crystallization of L2 lipase was still possible up to 70°C. Structural determination and comparison of microgravity and ground grown protein crystals have been carried out by using X-ray crystallography in order to investigate the effect of microgravity on the structure of protein crystals. It can be concluded that there was a polymorphism in L2 lipase crystals that resulted in production of two different shapes of protein crystals; Shape 1 and Shape 2. Shape 1 crystal can be produced both on Ground and in microgravity conditions, while Shape 2 crystal can only be produced on Ground. Both crystal structures of L2 lipase Shape 2 Ground and L2 lipase Shape 1 Space were refined and the final models were evaluated. Microgravity improved the quality of L2 lipase Shape 1 crystals where it was found that for the microgravity experiment, only Space-grown Shape 1 crystal can be diffracted and produced good diffraction data (diffracted at 2.3 Å), while its Ground-grown control Unit was not able to produce useful diffraction data. However, the best 3-D crystal structure was obtained by L2 lipase Shape 2 crystal with highest resolution (1.5 Å) as compared to crystal structures of L2 lipase Shape 1 crystals. The 3D structure of L2 lipase revealed topological organization of α/β-hydrolase fold consisted of 11 β-strands and 13 α-helices. Ser-113, His-358 and Asp-317 were assigned as catalytic triad residues. One Ca²⁺ and  Zn²⁺ were found in each of the molecules of L2 lipase. Both of the L2 lipase crystal structures gave values that were in the acceptable range of good protein structures when evaluated with Ramachandran plot, Verify 3D and Errat programs.