IgM antibodies are one of the fastest growing groups of diagnostic and therapeutic candidates. Unlike IgGs, IgMs cannot be purified by affinity chromatography due to their physiochemical properties. Furthermore, the large size of IgMs presents an additional purification challenge. We show the purification of an acidic IgM antibody with capture purification using Nuvia HP-Q anion exchange resin and polish purification using mixed-mode CHT Ceramic Hydroxyapatite Media. The capture step removed process-related impurities, while polishing with ceramic hydroxyapatite depleted these impurities further. The studies resulted in >99% IgM product purity, as measured by size exclusion chromatography (SEC) and SDS-PAGE analysis. This purity makes the IgM suitable for diagnostic applications. Additionally, this purification strategy is scalable and has potential for pharmaceutical applications.