The electrochemical detection of hydrogen peroxide in alkaline solution was performed on a La_0.7Sr_0.3Mn_0.75Co_0.25O₃ (LSMCO) nanofiber modified carbon paste electrode. Perovskite-type oxide LSMCO nanofibers were prepared by electrospinning and calcination. The morphologies, structures, and electrochemical behaviours of the nanofibers were characterized by scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction and cyclic voltammetry. The modified electrode shows excellent electrocatalytic activity towards hydrogen peroxide. Under optimal conditions, the linear response was obtained in the range of 0.5–1000 μM, with high sensitivity and a low limit of detection.