In the present work, we have studied the etching characteristics of Si{110} in 10M NaOH solution without and with addition of NH2OH. The etch rate of silicon and thermal oxide, and the undercutting rate at convex corners, which are important parameters to be known in the fabrication of MEMS structures using silicon wet bulk micromachining, have been studied in modified NaOH solution. The etch rate of silicon and the undercutting at convex corners increase significantly with the addition of NH2OH, while the etch rate of silicon dioxide reduces considerably with the addition of NH2OH etchant. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.