In the present study, possibilities for using novel nanocomposites based on alginate and silver nanoparticles for wound treatment were investigated in a second-degree thermal burn model in Wistar rats. Silver nanoparticles (AgNPs) were electrochemically synthesized in alginate solutions that were further utilized to obtain the Ag/alginate solution and microfibers for subsequent in vivo studies. Daily applications of the Ag/alginate colloid solution, containing AgNPs, alginate and ascorbic acid (G3), wet Ag/alginate microfibers containing AgNPs (G5) and dry Ag/alginate microfibers containing AgNPs (G6) were compared to treatments with a commercial cream containing silver sulfadiazine (G2) and a commercial Ca-alginate wound dressing containing silver ions (G4), as well as to the untreated controls (G1). Results of the in vivo study have shown faster healing in treated wounds, which completely healed on day 19 (G4, G5 and G6) and 21 (G2 and G3) after the thermal injury, while the period for complete reepitelization of untreated wounds (G1) was 25 days. The macroscopic analysis has shown that scabs fell off between day 10 and 12 after the thermal injury induction in treated groups, whereas between day 15 and 16 in the control group. These macroscopic findings were supported by the results of histopathological analyses, which have shown enhanced granulation and reepithelization, reduced inflammation and improved organization of the extracellular matrix in treated groups without adverse effects. Among the treated groups, dressings based on Ca-alginate (G4-G6) induced enhanced healing as compared to the other two groups (G2, G3), which could be attributed to additional stimuli of released Ca²⁺. The obtained results indicated potentials of novel nanocomposites based on alginate and AgNPs for therapeutic applications in wound treatments.