A continuous process and system for manufacturing beta-hydroxy-beta-methylbutyrate (HMB) and salts thereof is provided. The continuous process includes providing at least one oxidant and diacetone alcohol, and combining the at least one oxidant with the diacetone alcohol in a first flow reactor to produce a product stream comprising HMB or a salt thereof. Optionally, the process includes a second flow reactor for the acidification of a salt of beta-hydroxy-beta-methylbutyrate to produce beta-hydroxy-beta-methylbutyrate in free acid form.