Dibenz (b,f)-1,4-oxazepine (CR) is a new nontoxic skin irritant and is very useful as a riot control agent. A simple, specific and rapid Gas Chromatographic method with flame ionization detection for the determination of CR and its precursors and the process monitoring of the CR production is described. After a concise sample preparation, samples were injected on Gas Chromatograph (GC) column at 200degreesC for o-chlorobenzaldehyde (OCB) and 250degreesC for CR. In monitoring the process it was observed that in the first reaction 96.6% OCB was converted to Schiff's base (SB) within 25 min and 75% of potassium salt so formed by the reaction of SB with methanolic potassium hydroxide was converted into CR in 160 min. Repeatability of the described gas chromatographic method was evaluated by analyzing five replicates of the samples of OCB, SB and CR.