Sustainable technologies are increasingly promoted in various production areas. Protection of natural resources, as well as rational waste management, may lead to better optimization of technologies. Biochar, a product of pyrolysis of organic residues has found wide applications in waste management, agriculture, energy and construction industry. In the present study biochar samples produced in Poland and in Brazil were analysed for microbial content using three substrates: Plate Count Agar, Malt Agar, and Potato Agar. Both qualitative and quantitative measurements were done. Microscopic analysis of the biochar structure was also performed. We found that microbial cultures in both biochars represented a wide range of biodiversity of microorganisms genera and species. We demonstrate that the biochar samples differ depending on the botanical origin as well as on the production technology. Structure of the tested samples also varied depending on the botanical origin. Sample 1-PL (pine) was characterised by a compact and regular structure, while sample 2-PL (oak) showed porous and irregular structure. Sample from Brazil (1-BR) showed a more delicate structure than Polish biochars. Obtained properties may suggest a range of implications for practice.