Arrays of nozzles of uniform size and spacing (≃0.3 mm) suitable for high quality and high speed ink‐jet printing have been fabricated by the anisotropic etching of holes through (100) Si wafers using conventional Si‐processing techniques. The etchant used is a mixture of pyrocatechol, ethylene diamine, and water. The nozzles are well‐defined truncated, square pyramidal cavities bounded by 4 convergent {111} planes. The square orifice, side , is given by , where is the side of the square base and the wafer thickness. Successful fabrication of these silicon microstructures requires the application of well‐controlled patterning and etching processes and the selection of a uniform, defect‐free, accurately oriented single crystal substrate.