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Citizen Cosmotron X8 Chronomaster






In 1966, Citizen introduced the groundbreaking "Cosmotron": Japan's inaugural electronic watch. Departing from traditional designs, this innovation leveraged emerging technology to replace the conventional mainspring, marking a significant leap in watchmaking. While hybrid concepts had surfaced earlier, Citizen's creation stands out as the world's premiere authentic electronic wristwatch. It boasted a pioneering moving-magnet-type balance motor, powered by transistors on the regulating device—a testament to Citizen's relentless pursuit of innovation and precision.



The X8 Cosmotron series had a brief production span of around 10 years since the 1970s when the quartz revolution swiftly made older technologies obsolete. Despite its short history, the technology saw significant advancements, such as increasing the beat rate from 18,000bph to 43,200bph by the end of its run. These advancements, coupled with achieving chronometer standards, underscored the quality of the X8 movement. However, the relentless march of quartz modules eventually outpaced both its reliability and accuracy goals, marking the end of its era. The debut model of the X8 series, known as the 'Electric Watch,' showcased the innovative 0801 movement boasting 25 jewels. Today, we're offering the updated version, the X8 ChronoMaster, equipped with the upgraded 0802 movement. Notably, this variant introduced a 'Chronometer' grade version adorned with the dial's distinguished 'Electronic' logo.


Upon first glance, the X8 Chromonaster exudes a futuristic allure, a revolutionary design for the 1960s, complemented by its exceptional specifications, earning it the prestigious Good Design Award in 1969. The round case design, accentuated by index bars printed on the ring, evokes a sense of space-age aesthetics, a true reflection of its era. While the recessed crown may seem challenging to operate, it speaks to the watch's commitment to precision timekeeping, showcasing its intended functionality and striking design.


Initially priced at 34,000 JPY, the Chronomaster X8 we present is a flawless, unused example, complete with its original box, straps, and tags, with the protective film still intact on the caseback. Its allure is truly captivating once you hold it up close, particularly with its preserved factory lines on the case, making it a guaranteed standout piece in any collection.

Ships from Tokyo, Japan.

Citizen Cosmotron X8 Chronomaster

  • Overall, this Chronomaster is in immaculate condition. The case is very sharp and has all the factory lines intact. Expect some dirt and some hairline scratches since it's a deadstock.

    The original leather on the leather and buckle is immaculate with no sign of peeling. The glass has no visible scratches or chips.

    The caseback is beautiful with no visible scratches: The etchings are visible with the blue protective film still intact.

    The tags and the original box are in good shape.

  • BRAND:  Citizen
    MODEL: Cosmotron Chronomaster X8
    REFERENCE: 4502-8010
    DIAL: Original white dial
    CASE MATERIAL: Stainless Steel
    CASE DIMENSIONS: 39.5mm height, 37mm width, 11mm thickness, 18mm lug width
    CRYSTAL: Mineral Crystal
    CASE BACK: Screw-down Stainless Steel
    MOVEMENT:  Citizen Cosmotron 0802
    Manufacturing date: May 1966
    Service History: Unknown, battery replaced in 2024
    Bracelet/Strap: Original citizen leather belt with the correct Chronomaster buckle.

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