How much weight will you lose walking two hour on treadmill thirty days?

It really depends on your body weight. A person who weighs 250 pounds will burn more calories than someone who weighs 150. As someone who weighed in the 270's at one point, I burned about 400 calories just walking at a 3.0 for 60 minutes. As I lost weight, I noticed I wasn't burning as many calories while continuing to walk at a 3.0 for 60 minutes.