New effective nonwoven fibrous materials with bactericidal activity were electrospun from poly(3-hydroxybutyrate) and the iron(III) complex of tetraphenylporphyrin. Fiber surface defects were found to disappear if the iron(III) complex of tetraphenylporphyrin was added to the polymer solution. The supramolecular structure of fibers with encapsulated iron(III) complexes of tetraphenylporphyrin was investigated by DSC and EPR spectroscopy (probe method). It was shown that the degree of crystallinity increased sharply and molecular motion slowed in amorphous regions of the ultrathin fibers if the complex was added to the poly(3-hydroxybutyrate) matrix. The resulting fibrous materials possessed bactericidal properties and should be directly applicable to the fabrication of antibacterial and antitumor therapy systems.