Nitrides and oxynitrides are fascinating classes of compounds, known for interesting properties like refractory, mechanical, catalytic, superconducting and magnetic properties, used in a wide variety of technological applications. High-pressure synthesis is a powerful method for the synthesis of novel materials. High pressure synthesis using a large volume press (LVP) has the potential of discovering innovative materials during each experiment. Present talk will give a brief introduction to high-pressure synthesis technique along with discovery of tin oxy-nitrides (Sn2N2O), ternary silicon titanium nitrides (Si-Ti-N) at high-pressure, high-temperature (HP-HT) conditions. Recent results on HP-HT behaviour of amorphous Si-Hf-N compounds will be discussed with help of in-situ EDXRD data. Succeeding high-pressure synthesis of nanocomposites Hf3N4/c-Si3N4 will be presented.