A thermally insulating protective sleeve. The thermally insulating protective sleeve comprises a tubular shell and a thermally insulating liner located in the tubular shell and made of a thermally insulating soft material. The shell comprises two longitudinally separated half-parts, the two half-parts being detachably connected to each other. The thermally insulating liner defines a hollow opening in the shell, and an object to be thermally insulated can be received in the hollow opening in such a way that the thermally insulating liner is subjected to pressure in a radial direction.