Poly [ ( R )-3-hydroxybutyrate ] (PHB) constitutes a biopolymer synthesized from renew- able resources by various microorganisms. This work focuses on finding a new PHB-produc- ing bacterium capable of growing in conventional media used for industrial biopolymer production, its taxonomical identification, and characterization of its biopolymer. Thus, a bacterial isolation process was carried out from environmental samples of water and mud. Among the isolates, strain S29 was selected and used in a fed-batch fermentation to gene- rate a biopolymer. This biopolymer was recovered and identified as PHB homopolymer. Surprisingly, it featured several fractions of different molecular masses, and thermal prop- erties unusual for PHB. Hence, the microorganism S29, genetically identified as a new strain of Bacillus megaterium , proved to be interesting not only due to its growth and PHB accumulation kinetics under the investigated cu ltivation conditions, but also due to the thermal properties of the produced PHB