Statement of the problem. The artistic work of the Bukovynian composer and musicologist of the second half of the 19th – the first quarter of the 20th century Eusebius Mandyczewski plays an important role in the formation and development of the composer school of Bukovyna. The study of the cantata “The Power of Harmony” – one of Mandyczewski’s early works – is important, because it allows us to reveal the fundamentals, which contributed to his future artistic growth. Objectives, methods, and novelty of the research. The purpose of the study is a musicological analysis of the cantata “The Power of Harmony” by E. Mandyczewski and identification the characteristic features of the composer’s creative thinking. Such detailed analysis of the work revealing the characteristic features of the artistic style of the Bukovynian composer is the innovative component of the research. A set of methods that are important for identifying the features of a composer’s musical work was used: biographical, historical and cultural, method of musicological analysis, method of theoretical generalization. Results and conclusion. The artistic heritage of E. Mandyczewski is quite large, it covers various genres of musical work, but the most important one is the cantata genre. The study of the cantata “The Power of Harmony” revealed a number of features of the work and the stylistic foundations of the composer’s future mature work. The author demonstrated the skill of creating monumental genres and the ability to perform complex artistic tasks in a short period of time. We observe clear dramaturgy of the cantata, which is aimed at embodying the main idea of the work – an allegorical comparison of the harmony of the world, which grew out of chaos, with the formation of the musical culture of the Bukovynian region. This work reveals the composer’s romantic worldview, knowledge of the musical heritage of Western Europe, the style of foreign composers, and mastery of traditional writing techniques. E. Mandyczewski demonstrated the ability to operate a large group of performers, skillfully using the timbre of vocal voices and musical instruments. The expressiveness of the vocal melody is combined with the improvisation and virtuosity of individual instruments, in particular the violin, which is characteristic of the local performance tradition. High level of professionalism of the composer his mastery of the polyphonic writing technique attests: the use of polyphonic methods and forms, in particular the choral fugue, the use of timbre polyphony, etc. In the cantata “The Power of Harmony”, E. Mandyczewski, despite his young age, showed talent and professional mastery of instrumentation, harmony and counterpoint, as well as knowledge of the nature of the human voice. This early composer’s cantata was a great success during the first performance that gave the composer an impetus for future achievements.