The structure of silver modified powder cellulose isolated from hardwood lignocellulose was investigated using X-ray structural analysis and computer modeling. Full-profile analysis proved that the studied sample corresponds to the monoclinic phase of cellulose Iβ with an antiparallel arrangement of molecules. The unit cell parameters were a = 7.881 Å, b = 7.837 Å, c = 10.603 Å, and γ = 95.63°; the volume V = 652 Å3. The sizes of coherent scattering regions (CSR) of the sample calculated with a Scherrer method were determined to analyze the supramolecular structure. An increase of CSR was observed in the [100] direction and a decrease was found in the [001] direction compared to CSR of the powder lignocellulose. Cross-section area of the fibril of the modified sample in plane ab (980 Å2) was found to be ~8% larger than that of powder cellulose. The crystallinity index (CI) calculated with a Ruland method was found to be 79% which was 7% higher than that of powder cellulose. The final cluster of the silver containing powder cellulose had a chemical formula of C6O5H10.12Ag0.08.