A process for the production of high-purity isobutene by means of MTBE cracking, comprising the following steps: • feeding a stream containing MTBE to one or more fractionation columns for the purification of the MTBE, separating a stream containing MTBE and lighter compounds of MTBE, a stream of MTBE having a purity higher than 98% by weight and a stream containing MTBE and heavier compounds of MTBE; • feeding the stream of MTBE having a purity higher than 98% by weight to one or more cracking reactors obtaining an outgoing stream consisting of cracking products and non-converted reagents; • feeding said outgoing stream consisting of cracking products and non-converted reagents to a washing column with water, separating a stream containing isobutene, MTBE and light compounds at the head, and a stream containing methanol and water at the bottom, in turn sent to one or more fractionation columns for separating the water, to be recycled to the washing column, from the methanol; • feeding the stream separated from the head of the washing column to a fractionation column for separating the isobutene from the MTBE, obtaining a stream containing isobutene and light compounds at the head, and a stream containing MTBE and heavier compounds at the bottom; • feeding the stream separated from the head of the fractionation column containing isobutene and light compounds to another fractionation column for the purification of the isobutene, obtaining a stream containing light compounds at the head and a stream of high-purity isobutene at the bottom, wherein the stream containing MTBE and heavier compounds at the bottom of the fractionation column for separating the isobutene from the MTBE is recycled to the fractionation column (s) for purifying the MTBE. • feeding a stream containing MTBE to one or more fractionation columns for the purification of the MTBE, separating a stream containing MTBE and lighter compounds of MTBE, a stream of MTBE having a purity higher than 98% by weight and a stream containing MTBE and heavier compounds of MTBE; • feeding the stream of MTBE having a purity higher than 98% by weight to one or more cracking reactors obtaining an outgoing stream consisting of cracking products and non-converted reagents; • feeding said outgoing stream consisting of cracking products and non-converted reagents to a washing column with water, separating a stream containing isobutene, MTBE and light compounds at the head, and a stream containing methanol and water at the bottom, in turn sent to one or more fractionation columns for separating the water, to be recycled to the washing column, from the methanol; • feeding the stream separated from the head of the washing column to a fractionation column for separating the isobutene from the MTBE, obtaining a stream containing isobutene and light compounds at the head, and a stream containing MTBE and heavier compounds at the bottom; • feeding the stream separated from the head of the fractionation column containing isobutene and light compounds to another fractionation column for the purification of the isobutene, obtaining a stream containing light compounds at the head and a stream of high-purity isobutene at the bottom,