Polymer-derived ceramics (PDCs) are a promising alternative to powder-sintered ceramics because starting from liquid precursors allows compositional modification by adding functional fillers and shaping with high precision using microfluidics. Here, we present a facile and reliable process for the manufacturing of silicon carbonitride (SiCN) with tunable carbon content and microstructure. An organopolysilazane is used as the base precursor, mixed with a thermal initiator and divinyl benzene (DVB) ranging from 0 – 60 wt.%. The liquid mixture is thermally cured in molds and obtained green bodies (GBs) are transformed into ceramics by argon pyrolysis at 800 – 1400°C, undergoing 24 – 40% shrinkage and weight loss. The ceramics’ electrical conductivity is determined as a function of the precursor composition and pyrolysis temperature with values ranging from 5x10^(-11) – 1.3 S/cm. In combination with a good mechanical behavior (up to 2200 MPa flexural strength), these PDCs are currently investigated for their suitability for harsh environment and / or in-vivo biomedical applications.