Substituted allylic alcohols (2-buten-1-ol, 1-buten-3-ol, cinnamyl alcohol and 3-methyl-2-buten-1-ol) react with acyl isothiocyanates (4-chlorobenzoyl, 2,6-difluorobenzoyl, 3-phenylpropenoyl, 2-thienocarbonyl, 3-chloro-2-thienocarbonyl and 3-chloro-2-benzo[b]thienocarbonyl isothiocyanate) with the formation of highly reactive O-substituted allyl N-acylmonothiocarbamates, which either spontaneously or by heating in boiling benzene undergo [3,3]-sigmatropic rearrangement to S-substituted allyl N-acylmonothiocarbamates. The structure of S-esters with isomerized allylic group affords the unequivocal evidence of the [3,3]-sigmatropic route of studied rearrangement. Further heating of [3,3]-rearranged N-(4-chlorobenzoyl)monothiocarbamates results in the [1,3]-sigmatropic shift of monothiocarbamate group. Using arylalkyl alcohols with the allylic double bond inserted into an aromatic system the obtained O-esters either do not undergo any rearrangement (benzyl alcohol) or undergo [1,3]-sigmatropic rearrangement (2-and 3-furylmethanol and 1-(2-furyl)ethanol) to the corresponding S-esters. For explanation of this reaction the tandem of [3,3]-and [1,3]-sigmatropic rearrangements is suggested.The oxygen and sulfur containing 1,5-hexadiene systems of the type I (O-allyl monothioesters 1-4 , monothiocarbamates 5-8 , mono-3 and dithiocarbonates 6,9,10 ) are known to undergo a catalyzed or non-catalyzed [3,3]-sigmatropic rearrangement to compounds of the type II possessing the carbonyl and S-allyl instead of thiocarbonyl and O-allyl groups present in I. It was found 5,6 that substituents on allylic group, particularly α-methyl, accelerate the reaction I → II. Reactivity also depends on the nature of group R. O-Allyl monothioesters are less reactive than compounds with R bonded via heteroatom, e.g. O-allyl N,N-dialkylmonothiocarbamates. Reactivity of monothiocarbamates 2650 Ficeri, Kutschy, Dzurilla, Imrich: