Nanoporous (NP) PtNi alloy is easily fabricated through one step mild dealloying from PtNiAl source alloy. Characterized by three-dimensional nanosponge architecture with the typical dimension size as small as 3nm, the as-made NP-PtNi alloy exhibits superior sensing performance with superior sensitivity and low detection limit toward ethanol and H 2 O 2 as compared with state-of-the-art Pt/C catalyst due to its unique electrocatalytic activities. In particular, long-term sensing tests demonstrated that NP-PtNi alloy has distinct sensing durability with almost no activity loss upon continuous H 2 O 2 detection for two weeks. Along with these attractive features, the as-made NP-PtNi alloy also behaves a good anti-interference toward glucose, ethanol, ascorbic acid, uric acid, and dopamine during H 2 O 2 detection. NP-PtNi alloy shows great potential for electrochemical sensing applications.