The transport of oxygen from the lungs to tissues is one of the most important functions of blood. Gas exchange between blood and tissue occurs in the smallest blood vessels called capillaries. Elevated temperature, caused by factor such as external heat, can alter the properties of tissues and, in some cases, even cause thermal damage and thus disrupt the vascular system and oxygen delivery. One of the factors that can delay the appearance of hypoxia, that is, lack of oxygen in the body, is myoglobin, which is a protein that plays a role in local oxygen storage. The purpose of this study was to perform a numerical analysis of the thermal phenomena that occur in the three-dimensional domain of biological tissue exposed to external heat. Thermal analysis is based on the Pennes bioheat transfer equation. The degree of thermal damage is estimated using the Arrhenius scheme, and the tissue parameters are considered dependent on the temperature or damage levels. The thermal model is coupled to the model based on the Krogh cylinder. This model allows for an analysis of the changes that occur in the oxygen distribution in the capillary and surrounding tissue. The equation for the tissue subdomain includes components for oxygen consumption in the tissue and myoglobin saturation, while the equation for the capillary subdomain considers blood saturation and its dependence on partial oxygen pressure. The models are linked by the relationship between blood velocity in the capillary and perfusion coefficient. In the numerical implementation stage, the finite difference method and the shooting method were used. Changes in oxygen partial pressure in the tissue due to the effects of increased temperature, which affect tissue perfusion and capillary blood velocity, are easily observed. Myoglobin influences the distribution of oxygen partial pressure and causes resistance to local tissue hypoxia by releasing stored oxygen in tissues. Acknowledgement The research is financed from financial resources from the statutory subsidy of the Faculty of Mechanical Engineering, Silesian University of Technology in 2024. REFERENCES [1] M. Jasiński, M. Zadoń, Modeling of the influence of elevated temperature on oxygen distribution in soft tissue, Engineering Transactions, 71(3): 287-306, 2023. [2] J.P. Whiteley, D.J. Gavaghan, C.E.W. Hahn, Mathematical modelling of oxygen transport to tissue, Journal of Mathematical Biology, 44: 503–522, 2002.