In recent years geopolymers have shown increased interest as binders with low CO₂ emission compared to Portland cement. The main goal of this research is focused on connecting green and sustainable characteristics with the mechanical and chemical properties of fly ash-based geopolymer. The samples of different ratios of fly ash (FA) and metakaolin (MK) were prepared. X-ray powder diffraction (XRD) showed that in the geopolymer synthesis reaction a new amorphous phase was formed. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) confirmed characteristic bands of the Si-O and O-Si-O groups at 1045 cm⁻¹. Compressive strength analysis revealed that the optimal ratio of FA and MK is 50:50 and exhibits the highest value. X-ray photoelectron spectroscopy (XPS) analysis revealed the total reduction of carbon content in the alkali-activated geopolymer with the optimal stoichiometry of 50:50. This indicates the possibility of obtaining a geopolymer material with an almost complete absence of carbon, which implies further application as a material with a very high environmental potential and of zero carbon emissions.