Boron is one of the hardest materials known, and therefore, a promising pathway to achieve high-strength materials is the development of borides, which attracts increasing interest in recent years. While binary, ternary and even quaternary transition metal (TM) nitrides have been studied in detail by experimental and computational materials science, there is only limited information available about TM borides, especially when prepared with physical vapor deposition techniques. Transition metal diborides (MeB2) have a wide variety of promising properties such as high hardness, high wear resistance, low friction and high conductivity. An excellent example is the superhard NbB2 (42 GPa) with low a friction coefficient (0.16) obtained by Nedfors et al.. However, due to a high demand for new materials, binary systems cannot fulfill the newly asked requirements. An interesting approach for improving material properties of sliding electric contacts is the development of ternary borides, where the third element should improve the electric properties while retaining the tribological properties. Silver is one of the best conducting materials, thus it not only retains but even improves the electrical properties. Furthermore, by the addition of Ag also the tribological properties and the toughness are improved. Therefore, we develop materials within the Nb-Ag-B system, where especially (Nb,Ag)B2 phases are of particular interest. However, while there are at least a few reports about NbB2 thin films, there is only limited and moreover contradictive information available on a crystalline AgB2 phase. Based on our results we can conclude that a crystalline AgB2 phase is not accessible within the wide variation in deposition conditions used during physical vapor deposition. Moreover, newly developed ternary Nb-Ag-B thin films show only crystalline NbB2 phases with no indication for a solid solution Nb1-xAgxB2. For an Ag/(Ag+Nb)-ratio of 0.4, the films exhibit crystalline silver phases next to NbB2 nanocrystallites. An increase of Ag-content up to Ag/(Ag+Nb)= 0.81 results in a continuous deterioration of hardness from 31 to 2.3 GPa, but also in a significant reduction of compressive residual stresses from 2.3 to 0.13 GPa and friction coefficient from 0.91 to 0.35.