A steady state global (volume averaged) model is developed for the chlorine discharge using a revised reaction set. Various calculated plasma parameters are compared with measurements found in the literature, showing a good overall agreement. The reaction rates for the various reactions are evaluated in the pressure range 1–100 mTorr. In particular, we explore the dissociation process as well as the creation and destruction of the negative ions Cl⁻. The discharge is highly dissociated throughout the pressure range explored, 1–100 mTorr, even when the absorbed power is low. The mechanism for Cl creation is complex. Although electron impact dissociation dominates with roughly 60–65% contribution, mutual neutralization of positive and negative ions and dissociative electron attachment are important contributors to the production of Cl atoms at high pressure. The electronegativity increases rapidly with decreasing dissociation fraction since the Cl⁻ ions are created entirely by dissociative electron attachment, predominantly from Cl₂(v = 0), but also up to 14% from Cl₂(v > 0) at 100 mTorr. The negative ion Cl⁻ is lost almost entirely through mutual neutralization with at high pressure while Cl⁺ has a significant contribution at low pressure.