The structural and electrical characterisation of CdTe epilayers grown by H-2 transport vapour phase epitaxy (H-2 T-VPE) on ZnTe/(100)GaAs is reported. Double-crystal X-ray diffraction measurements indicate the material high crystalline quality, leading to (4 0 0) peak FWHM of 59 arcsec for similar to 30 mu m thick epilayers. CdTe grown at temperatures T-D < 650 degrees C are p-type, but turn to n-type for T-D > 650 degrees C, For 650 degrees C < T-D < 700 degrees C, room-temperature (RT) resistivity in the 10(5)-10(6) Ohm cm range is obtained. Nail measurements performed on n-type samples of different thicknesses grown at T-D = 764 degrees C show RT carrier concentrations in the 10(14)-10(11) cm(-3) range. For a 22 mu m thick epilayer two donor states are found: the most abundant one almost compensates a 10(18)cm(-3) density of accepters; the second donor, having an ionisation energy E-D = 0.186eV, determines the sample n-type properties, its concentration being similar to 10(15) cm(-3) A compensation ratio K greater than or equal to 0.9997 holds for this epilayer. It is suggested that Ga diffusing from GaAs into CdTe gives rise to the above donor states.