Chitosan is the only natural polycationic polymer whose properties such as biocompatibility, biodegradability and non-toxicity make it ideal for use in agriculture, food and cosmetics industry, wastewater treatment, tissue and bone engineering and as a drug delivery system. Depending on the application, it is possible to prepare chitosan-based materials in the form of emulsions, films, and micro- and nanoparticles, which have proven to be ideal drug carriers. In order to achieve the desired drug release kinetics, and thus successful tumor treatment, it is necessary to prepare micro- and nanoparticles with a controlled size distribution, morphology and structure. Some of the methods used to prepare chitosan microparticles are electrospraying, spray drying, emulsion and precipitation methods. In this work, the electrospraying process was used for the preparation of microparticles. Composite microparticles based on chitosan‒copper(II) ions complex and hydroxyapatite (CHT-Cu/HAp) were prepared, while the influence of the addition of hydroxyapatite on the properties and drug loading efficiency of the antitumor drug (doxorubicin, DOX) was investigated. Dry microspheres were analyzed using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray diffraction analysis (XRD), and the results indicated the presence of interactions between the polymer matrix and the filler. The size and shape of the microspheres were determined using an inverted light microscope. The sphericity of the prepared microparticles was observed, while the smallest microparticles with the narrowest size distribution were obtained for the system with 5 wt.% HAp (CHT-Cu/HAp5). At a higher content of hydroxyapatite (10 wt.%), larger microparticles with a wider size distribution were obtained due to the instability of the electrospraying process. The swelling degree of CHT-Cu/HAp microparticles increased at lower pH value of the incubation medium and at higher content of hydroxyapatite. Fluorescence spectrometry and the gravimetric method used to analyze the drug loading into the prepared CHT-Cu/HAp microparticles indicated unexpected results; therefore, further investigation is needed to assess the effectiveness of DOX.