Over the past few decades, transition metal catalyzed C-H activation has been immensely investigated due to the ability to functionalize relatively unreactive C-H bonds whilst simplifying synthetic schemes and making the synthetic pathway more economical. Nowadays, a great emphasis has been placed on substitution of noble metal catalysts (Pd, Rh, Ru, etc.) with more abundant and cheaper alternatives (Cu, Co, Ni). The aim of the Doctoral Thesis is the development of novel cobalt catalyzed C-H bond functionalization methodology. The Doctoral Thesis is prepared as a collection of publications. The main results of the Thesis were summarized in 4 scientific publications, 3 review articles and 2 book chapters.