High-quality Tl2Ba2CuO6+δ (2201) compounds were synthesized using a high-pressure route. Starting from Tl2Ba2O5 and CuO, the reactions yielding either the orthorhombic or the tetragonal (superconducting) phases were carried out under 100 bar of oxygen or argon and helium, respectively. Preferential thallium losses are prevented and high sintering temperatures can be used to obtain pure samples with large 2201 grains. The experiments performed include metallographic examinations, X-ray diffraction, microprobe analysis, plasma emission spectroscopy, HRTEM, AC susceptibility, Meissner field cooling, hysteresis loops, normal-state susceptibility and specific heat measurements.