Photodynamic therapy (PDT) is a type of tumor therapy that involves the accumulation of photosensitizers in the tumor tissue where, after illumination with a certain wavelength in the presence of oxygen leads to the direct death of the tumor cell, damage to the microvasculature and the induction of a local inflammatory reaction. Due to their favorable physical and chemical properties, porphyrin-type compounds are often used as photosensitizers in PDT. When choosing photosensitizers, desired characteristics include non-toxicity without radiation, efficient absorption of the light in the visible spectrum, generation of singlet oxygen and other reactive oxygen species, but also an optimal ratio of hydrophilic and lipophilic properties for effective intravenous administration and facilitated penetration into the tumor tissue. In addition to hydrophilic and lipophilic properties, the structure and the charge of the photosensitizer determine its pharmacokinetic and pharmacodynamic properties. Compared to zwitterionic (oxido)pyridylporphyrins, cationic O-alkylated (oxido)pyridylporphyrins have the potential for better solubility in biological solvents and more effective penetration and binding to tumor tissues. O-Ethylated (oxido)pyridylporphyrins synthesized with dichloromethane as solvent and ethyl tosylate as alkylating reagent were successfully isolated. Synthesized 5-(4-acetamidophenyl)-10,15,20-tris(1-ethoxydopyridin-3-yl)porphyrin trichloride (porphyrin 8) showed a better solubility in the biological medium and higher intensity of the absorption and emission spectrum compared with porphyrin 4 and lower IC50 values on breast cancer cells (MDA-MB-231) after illumination with a red light lamp (λ = 645 nm, 3,6 J/cm2 ) compared to their precursors (porphyrin 4 and porphyrin P).