Conventional ion plating theory assumes that the metal vapor arrives at the substrate in monatomic form. Our results suggest this is not the case, and that a large proportion of the metal arrives as clusters. This is based on measurements of the cathode fall distance before and during titanium deposition in a thermionically supported argon glow discharge. The results have been used to evaluate the charge‐to‐mass ratio of the metal species in accordance with the Child–Langmuir equation. This predicts that some titanium is present as atomic clusters which contain at least tens of atoms per unit charge. Also we show that at least 90% of the ion current arriving at the substrate is carried by the metallic species.