A low-temperature hydrothermal method was developed to synthesize red phosphor lanthanum molybdate doped with [Formula: see text] ions. SEM, XRD, FTIR, Raman, UV–Vis DRS and photoluminescence patterns were employed to characterize information of the sample’s morphologies, phase structure and properties. The calcination temperature was determined by TG-DTA results. Thorough energy transfer happened between [Formula: see text] ions and phosphors in water solution. So, the prepared materials provide an excellent sensing platform for ferric ions, which have potential applications in biotechnology and environmental protection.