The chemical studies, which led to the testing of allyl-iso-propyltelluride (allylTePr(i)) as a Te precursor in metal organic vapour phase epitaxy are presented. The pyrolysis in hydrogen of allylTePr(i) gave products including 1,5-hexadiene, propane and propene. Co-pyrolysis of dimethylcadmium (Me2Cd) and allylTePr(i) gave the hydrocarbons expected from the pyrolysis of the individual precursors plus additional hydrocarbons including 2-methylpropane and l-butene, Plots of percentage decomposition versus temperature, which proved extremely useful in determining the likely growth temperatures for both CdTe and HgTe, showed that allylTePr(i) is less stable than both (Pr2Te)-Te-i (di-iso-propyltelluride) and Me2Cd. The possible role of Hg in the growth of CdTe is also discussed. The chemistry of allylTePr(i) is well suited for use as an efficient precursor for epitaxial growth of tellurium containing semiconductors since there is very little formation of other organotellurium compounds on pyrolysis. Crown Copyright