The pyrolysis of 10β-pinane-2,3α-diol 48, 10β-pinane-2,10-diol 47, 2,3-epoxy-10β-pinane 51 and 2,10-epoxy-10β-pinane 57 are described. The products result from (C2)-O bond cleavage and there is a marked similarity in product mixtures between the corresponding diols and epoxides. Mixtures of cis- and trans- 2,2-dimethyl-1-(2-hydroxyethyl)- 3-hydroxymethylcyclobutanes (64 and 65) and cis- and trans-2, 2-dimethyl-1-(2-methoxyethyl)-3-methoxymethylcyclobutanes (72 and 73) were pyrolysed at temperatures greater than 600°C. The configuration at C(1) and C(3) was found to be important in determining the path of cyclobutane cleavage. The trans-compounds 65 and 73 showed a marked bias to give products resulting from cleavage of the C-C bond adjacent to the axial substituent.