Biocomposite is a subtype of natural composite that is made of a natural matrix, biomass, and natural reinforcement, a network of intertwined hyphae, called mycelium. Mycelium is the vegetative underground part of fungi that has a great ability to reproduce. Therefore, biocomposites are completely of biological origin and biodegradable, and an example of a circular economy, profitable and economical. Biomass, most often lignocellulosic, is collected from the agricultural or forestry industry, shredded and sterilized to create a suitable medium for the growth of mycelium, i.e. a substrate, which must be compatible with the selected type of mushroom, because this is the only way the growth will be successful. After sowing mycelium, growth and development will only take place under favorable conditions, namely a temperature higher than 20 ℃ and humidity above 60 %. After the substrate is completely whitened, further processing of the material follows. The material is processed in various ways that include drying, cold and hot pressing. The resulting biocomposites can be used in everyday life such as: lightweight packaging materials, furniture, building materials, sound insulation and wall cladding, clothing and many others. That was the goal of this work, to obtain a stable solid biocomposite based on mycelium of oyster mushroom. It was found that there is no significant difference in germination, and therefore strength, which was manually tested, between the biocomposite of pure straw and straw and hemp. It has been confirmed that germination is affected by the pH of the substrate after sterilization and the inflow of fresh air. Also, it has been proven that the different finishing of the material affects the final product.