This paper explores the application of acoustic emission (AE) monitoring in mechanical and materials studies, specifically focusing on the detection of plastic deformation, fracture, and crack growth. However, the influence of high temperature on AE signals and its effects on mechanical properties are not fully understood due to the limitations of sensors in high-temperature environments. To address this gap, the study investigates the impact of high temperatures on the mechanical properties of stainless steel SS304 using AE techniques during tensile testing. Two temperature conditions were tested: 600 and 700°C. AE sensors connected to specimens captured AE activity using a designated waveguide, and a Continuous Creep Monitoring Instrument (CCMi) recorded the responses. Sensitivity testing using the pencil-lead break (PLB) technique ensured the sensor's capability. The proposed frequency-based analysis method, fast Fourier transform amplitude (FFTA) analysis, was employed to effectively analyze the AE signals. The results revealed significant AE features and frequency distributions associated with elastic deformation, plastic deformation, and fracture regions. These findings establish a foundation for utilizing AE techniques in crack detection and monitoring under high-temperature loading, contributing to equipment reliability and structural integrity. © 2023 American Institute of Chemical Engineers.