Silicon nanostructures are synthesized with a DC atmospheric pressure microplasma jet using an Ar/SiH4/H2 gas mixture. The plasma is characterized by OES and imaged using an EMCCD camera. The effect of hydrogen admixture to the formed structures is studied by transmission electron microscopy. Under specific conditions, crystalline silicon nanoparticles grow in an amorphous matrix investigated by electron energy loss spectroscopy. As‐grown silicon nanoparticles are collected in ethanol for dynamic light scattering and photoluminescence measurements. The size distribution peaks at 4 nm. The silicon nanocrystals exhibit roomtemperature photoluminescence that peaks at ∼415 and ∼465 nm.