AbstractA new series of heterocyclic oximes, prepared by the quarternization of 4‐hydroximino‐methylpyridine with various aminoalkyl halides, have been tested as reactivators of phosphorylated cholinesterase. With the most active member, 4‐hydroximinomethyl‐l‐[3(N, N‐dimethylamino)‐n‐propyl]‐pyridinium chloride, the rate of reactivation is comparable to that obtained with the known diquarternary compound, TMB‐4. These findings shed new light on the mechanistic concept of the r