The aim of the study was to evaluate the biogas profitability of silages made of whole crop maize ensiled with the addition of inoculant, containing strains of Lactobacillus genus from species that stimulate the synthesis and/or metabolism of 1,2- propanediol to propionic acid. As a result of the experiments on the synergistic action of bacterial strains an inoculant composition Lactosil Biogas Plus has been developed, which contains the following bacterial strains: L. buchneri A KKP 2047 p, L. diolivorans K KKP 2057 p and L. reuteri M KKP 2048 p. Silages made of whole crop maize with the addition of the inoculant Lactosil Biogas Plus were prepared under production conditions at the experimental station. Based on the results of the silage analyses, it was found that the effect of inoculant in the ensiling process resulted in the improvement of their microbiological purity expressed by pathogenic bacteria elimination such as bacteria of the genus Salmonella and Escherichia coli species and by fivefold reduction of molds. In the experimental silages increased content of acetic acid, 1,2- propanediol and propionic acid was observed and their aerobic stability was 192 hours, while the aerobic stability of silages prepared without the addition of inoculant was only 96 hours. Thus the experimental silages subject to methane fermentation by laboratory method allowed to achieve the biogas yield higher by 60.2 NI kg dry organic matter-1, the methane content of the biogas higher by 6.4 percent relative to the standard silage without the addition of the inoculant.