Assessing and optimizing human indoor comfort is challenging as physiological, psychological, and environmental variables influence it. Therefore, it is crucial to understand variability of human physiological parameters and underlying mechanisms. Metabolic rate and sitting behavior can affect body's thermal balance and thermal comfort across various thermal exposure. This study aims to understand human sitting behavior in different thermal exposure and its effect on metabolic rate in office work environment. The two whole day experiment involved 12 healthy female subjects performing typical daily office tasks in a climatic chamber set at neutral (24°C) and cooler (18°C) temperatures. The results demonstrated that the dynamic sitting was generally higher in the cooler thermal exposure compared to the neutral environment. However, the relationship between dynamic sitting and metabolic rate showed considerable inter-individual variability.