its economic and environmental advantages, biomass, with its inherently complex nature, presents diverse molecular structures that can be tailored into functional materials suitable for versatile applications. For example, biomass-derived carbon materials exhibit many desirable properties for electrocatalysis, including good wettability, conductivity and chemical stability. Modification of biomass derived carbons with metal active sites enabled electrocatalysts with high catalytic activity, selectivity and durability for many electrochemical processes. Recent studies have demonstrated carbon-based ORR electrocatalysts derived from zoomass and phytomass. These catalysts typically contain nitrogen (N), sulphur (S), phosphorus (P) heteroatoms, which serve as chelating sites for metals and also boost electrical conductivity. Their multifaceted composition gives biomass-derived carbons additional functionality compared to traditional carbon materials used in electrocatalysis (e.g. carbon black or Ketjenblack). Furthermore, biomass originating from livestock, specifically blood derived from the meat processing industry, is commonly treated as waste and discarded. This blood biomass contains haemoglobin (Hb), comprising four polypeptide chains housing a Fe-porphyrin moiety, rendering it a potential ORR electrocatalyst. Consequently, the processing of animal blood biomass holds significant promise for fabricating Fe-based ORR electrocatalysts. Several blood biomass-derived electrocatalysts, prepared using Hb in combination with electrically conductive carbon or carbon nanotubes, have been reported. However, these approaches typically necessitate an additional Fe source and a two-step pyrolysis process to achieve optimal ORR performance. The use of an additional Fe source is not desirable, with the development of better electrocatalysts using Hb as the sole Fe source requiring judicious selection of other precursor materials. Lignin, a carbon-rich material, is known to have a favourable interactions with metal ions, making it a suitable material for making catalysts with Hb. Lignin is the most abundant aromatic biopolymer and a renewable resource produced by the pulping Kraft industry. Its versatility extends to various applications, including serving as a carbon support, catalyst and adsorbent. Recent attention has focused on the π-π stacking interactions and hydrogen bonds between lignin and structurally similar tannins, demonstrating synergistic interactions with metals and underscoring their catalytic potential. Notably, tannins (water-soluble polyphenols with a macromolecular structure) have a strong binding affinity to proteins via noncovalent interactions, suggesting they would be useful when making catalysts with proteins like Hb. Herein, we aimed to develop efficient ORR electrocatalysts using haemoglobin, tannic acid and lignin (with urea added as additional N and C source). The precursors were selected due to their low cost and facile processing. We hypothesised that pyrolysis of powder mixtures of Hb, tannic acid, lignin and urea would create S,N-codoped carbons supporting porphyrin-like Fe sites. The S-and N-coordination of Fe on the carbon surface would facilitate electron transfer and boost ORR performance. By benchmarking the performance of the obtained FeSN/C catalysts with a commercial 20 wt.% Pt/C catalyst, we sought to demonstrate the future potential of biomassderived catalysts in future energy conversion and storage systems.