Gold nanoparticles (AuNPs) were in situ electrodeposited on n-type GaN (n-GaN) electrode via cyclic voltammetry for electrochemical sensing of hydrogen peroxide (H2O2). Detection results revealed the H2O2 detection range was from 40 mu M to 1 mM, and the detection limit was 10 mu M, moreover, AuNPs/n-GaN electrode showed quick response (less than 1 s) and high sensitivity (164.0 mu A mM(-1)) toward H2O2 detection. Furthermore, AuNPs/n-GaN electrode exhibited good selectivity, and excellent mechanical and storage stability. In addition, AuNPs/ n-GaN electrode showed accurate responses toward diluted human serum samples with 50 mu M H2O2, which indicated AuNPs/n-GaN electrode has potential for biomedical study.