The aim of the research to determine the effect of thermal modification to Improve the antibacterial spectrum of hen egg white lysozyme (HEWL) particularly in gram-negative bacteria. The method used is the experiment with completely randomized design (CRD) that treatment 40o C, 45oC, and 50oC for 20 minutes and control each was repeated 3 times. Observed variables include lysozyme activity, lysozyme recovery and specific activity of lysozyme on M.lysodeikticus and E. coli, MIC and molecular weight protein fractions. The results showed that the thermal modification with different temperature treatment gave significant effect (P <0.05) to increase the antibacterial spectrum of egg white lysozyme. Treatment temperature of 50o C for 20 minutes on the hen egg white lysozyme extract yield is 12.92% the highest inhibition against gram-negative bacteria (E. Coli) with a concentration of 1.18 mg /ml.