In this work, hollow CoS2 particles were prepared by a one-step sulfurization strategy using polyoxometalate-based metal-organic frameworks as the precursor. The morphology and structure of CoS2 have been monitored by scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray powder diffraction. The mechanism for the formation of CoS2 is discussed. The reaction time and sulfur content are found to be important factors that affect the morphology and pure phase formation of CoS2, and a hollow semioctahedral morphology of CoS2 with open voids was obtained when the sulfur source was twice as large as the precursor and the reaction time was 24 h. The CoS2 (24 h) particles show an excellent peroxidase-like activity for the oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) to blue oxidized (oxTMB) by hydrogen peroxide. The polyoxometalate used as a precursor helps to stabilize oxTMB during catalytic oxidation, forming a stable curve platform for at least 8 min. Additionally, the colorimetric detection of hydroquinone is developed with a low detection limit of 0.42 μM. This research provides a new strategy to design hollow materials with high peroxidase-mimicking activity.