Abstract <p>Porous anodic aluminum oxide (PAAO) due to its accessible manufacturing technology and unique physical and chemical properties has found wide application in various fields of science and technology. The PAAO is formed in sulfuric acid and consists of ordered arrays of pores with an average diameter in the range 10–15 nm. However, for samples synthesized at the electrolyte temperature of 40°C, the surface becomes disordered and consists of individual thread-like fibers. For the first time, paramagnetic centers (defects) were identified and their influence on PL of analyte (Rhodamine B) was studied in a series of samples obtained in a wide temperature range: 5–40°C. It was established that in PAAO formed at 5°C oxygen vacancies (F⁺ centers) are detected. In samples synthesized at higher temperatures Al–SO₄ paramagnetic complexes are additionally observed, the maximum concentration of which is achieved in samples obtained at an electrolyte temperature of 25°C and is more than an order of magnitude higher than the concentration of F⁺ centers. The minimum PL intensity of the Rhodamine B was found in samples with the highest concentration of paramagnetic centers. This effect is due to the fact that part of the exciting radiation is absorbed by paramagnetic centers (Al–SO₄ and F⁺), therefore the PL of the dye decreases. Therefore, it is possible to control the type, concentration of paramagnetic centers in PAAO and the intensity of photoluminescence of the dye in its pores by varying the temperature of the electrolyte and dye concentration. The obtained results may be useful in the development of PAAO-based optical sensor platforms.</p>