Aluminum oxide was used to insolubilize (i.e. to lake) riboflavin 5′-phosphate (FMN) to improve the light stability of vitamin B2. HPLC was used to determine adsorption percentage and light stabilities of laked FMN. The adsorption of FMN on aluminum oxide was very effective. An FMN content of 55% in lake was achievable, with adsorption of 91%. The adsorption isotherm was of the Langmuir class, and differed from the desorption isotherm. The stabilities of laked FMN at different light intensities and aw values were significantly (p=0.05) higher than those of free FMN.