Polyextremophilic organisms, such as haloalkaliphiles have focused attention due to their hydrolytic enzymes. The halophilic microorganisms include heterotrophic and methanogenic archaea; photosynthetic, lithotrophic, and heterotrophic bacteria; and photosynthetic and heterotrophic eukaryotes. Halophiles and haloalkaliphiles are distributed throughout in hypersaline environments, natural hypersaline brines in arid, coastal, and even deep sea locations, as well as in man-made salterns. The microbes possess range of the biocatalysts which allow them to sustain under the prevailing extreme conditions. Among the enzymes, proteases, carbohydrases, and peroxidases are the most cited candidates. The proteases widely occur in microbial world and play significant role in the processing and maintenance of large number of membrane proteins under the cellular conditions. Besides, the proteases are among the commercially most viable enzymes and dominate the worldwide enzyme market. The proteases of halophilic and haloalkaliphilic bacteria from the marine sources appear to have significant role in the detergent industries, ripening of the salted fish, fish sauces and marinades, modifying fish protein concentrations, dehairing and deskinning, non aqueous enzymology and asymmetric catalysis. In the present chapter, the proteases from the halophilic and haloalkaliphilic bacteria have been reviewed with respect to their occurrence and biochemical properties.