NOVELTY - Providing an alkylatable process in which there is no need to remove the alkylate from the reactor system before cycling from the regeneration to the alkylation mode.    USE - For continuous alkylation.    ADVANTAGE - The reactors in zones (A,B) can cycle between the alkylation mode and the regeneration mode by switching a few valves, instead of injection points having to be moved. Moreover, instead of two separate alkylatable compound-containing streams that is feed stream and regenerant stream, only one hydrocarbon-containing stream (alkylatable compound-containing stream) is required. The alkylate remains unconverted when present during regeneration of the catalyst with hydrogen. Therefore, there is no need to remove the alkylate from the reactor system before cycling from the regeneration to the alkylation mode.    DETAILED DESCRIPTION - An alkylatable compound is reacted with an alkylation agent in the presence of a solid acid alkylation catalyst to form an alkylate in an apparatus comprising a series of at least two catalyst-containing reactors (4A,5A) in zone (A) and a series of at least two catalyst-containing reactors (4B,5B) in zone (B). The catalyst is regenerated and the alkylate is recovered. Zones (A,B) reactors cycle back and forth per zone between alkylation mode and mild catalyst regeneration mode. The alkylation mode involves introducing alkylation agent into a first reactor of the zone through which alkylatable compound passes, reacting a portion of the alkylatable compound with at least a portion of the alkylation agent to produce an alkylate-containing product stream and performing the operation at least once more in a downstream reactor of the same zone, using instead of alkylatable compound a stream comprising alkylate-containing product stream which may or may not have been subjected to prior intermittent separation, during which a portion of the alkylate has been removed to produce an alkylation mode alkylate-containing effluent. The mild regeneration mode involves contacting the solid acid alkylation catalyst with hydrogen in each of at least two reactors of the zone.    DESCRIPTION OF DRAWING(S) - The figure shows the schematic lay out of the above apparatus used for continuous alkylation.    Catalyst-containing reactors (4A,4B,5A,5B)    Valve systems (1A, 1B, 7A, 7B)    Ducts (2A, 2B, 8A, 9A, 8B, 9B, 11)    Inlets (3A, 3B, 6A,6B)    Separation unit (10)