The research effort in the field of Hot Wire CVD (also called Catalytic CVD or initiated CVD) has increased considerably over the last 10 years. An increasing variety of thin film materials can be obtained with this method, with good feedstock utilization and high deposition rate. The properties of the deposited films are notably different from those of films made with conventional methods. A number of applications, such as diamond deposition, functional polymer deposition, and passivating silicon nitride deposition, have already found its way to commercial manufacturing. In this paper we discuss some of the modern research issues in the realm of Hot Wire CVD (Cat-CVD) and i-CVD. (C) 2009 Elsevier B.V. All rights reserved.