This paper reports the use of hot-wire chemical vapour deposited (HWCVD) Silicon nitride as a passivation layer for Organic Field Effect Transistors (OFETs). Firstly, the degradation study of the OFETs is done with time. A thin (10-20 nm) layer of silicon nitride is deposited on the OFETs, at a low temperature (<90 degrees C) by HWCVD process, to passivate them from the ambient. Our results show that this technique is very effective in improving the stability of the organic semiconductors (Poly-3-hexyl thiophene (P3HT) is used as a test case in this study). This HWCVD deposited nitride can also be used as a gate dielectric material for the study of OFETs because of its higher dielectric constant and significantly less hydrogen content. (c) 2007 Elsevier B.V. All rights reserved.