Abstract: A bacterial species identified as Bacillus megaterium GS1 was previously isolated from volcanic area of Gunung Sibayak, Indonesia. Therefore, the main aim of the present study was to identify the presence of dehalogenase gene in the microorganism. To achieve this, is to apply basic molecular techniques that include the use of oligonucleotide primers specific to microorganism that can grow in halogenated compound. A putative dehalogenase gene was determined by direct sequencing and analysis of the PCR-amplified genomic DNA of the bacterium. A comparative analysis of the sequence data revealed that, DehGS1 amino acid sequence is related to L-specific dehalogenase or group II αHA with an overall of 25% amino acids identity. This investigation is useful in studying the microbial populations in order to monitor the presence of specific or novel type dehalogenase genes. As a result, it will provide better understanding of the microbial populations that present in soil or in water systems treating halogenated compounds.