Is it normal for a master brake cylinder to make hissing noise?

No, a hissing noise from a master brake cylinder is not normal. It indicates a leak in the system, which is a serious safety issue. A leak means your brakes will not function properly, potentially leading to brake failure.

The hissing sound is the pressurized brake fluid escaping through the leak. You should immediately have your vehicle inspected by a qualified mechanic to locate and repair the leak. Driving with a leaking master cylinder is extremely dangerous.