The work presents materials characteristics of fibrous polysaccharide substrates (calcium alginate, CA) modified with short peptides. Three types of synthesized peptides (hexapeptides) were composed of: cysteine (C) and tryptophan (W) named - (WWC)2 or cysteine (C) and tyrosine (Y) named (YYC)2 or phenyloalanine (F) named 6F. The peptides size distribution (DLS method) showed that they agglomerated in an alcohol medium. These results were used to select a modification method of the fibrous substrates i.e. the peptides were deposited on the fibrous alginate substrate by the electrospraying technique. Using this method three kinds of polysaccharide- peptides systems were obtained i.e.: CA/(WWC)2, CA/(YYC)2 CA/6F. As a reference material, the pure calcium alginate fibrous substrate was used. The results of modification with short peptides were evaluated via scanning electron microscopy (SEM): small aggregates were observed (40-100 nm) on the surface of fibers, and the fibers size remained the same after modification (11-12 µm). The size of aggregates depended on the kind of short peptide; the smaller (40 nm) aggregates were observed when the peptide had only aromatic chain (6F), the bigger (<100 nm) ones were observed when the peptide had heterocyclic rings in the chain (WWC and YYC). All materials were contacted with osteoblast-like cells (MG-63) to test biocompatibility (cells viability after 3 and 7 days) and the results proved showed higher viability in the polysaccharide-peptide system which increased with the time of observation. The durability of polysaccharide-peptide systems was tested using the enzymatic assay: collagenase confirmed the stability of materials. The progress of degradation rate was observed using infrared spectroscopy (FTIR-ATR) - the ratio on bands with C-O and C-OH increased after degradation under in vitro conditions. Results of the investigations on the fibrous substrates have confirmed that the system is a good model of an extracellular matrix (ECM) due to its chemical composition and microstructure which both have biomimetic characteristics. Thus, it may be used as a filling of bone defects supporting the regeneration of the damaged tissue. Additionally, it may also serve as the model research system of ECM.