In a vacuum, both X-rays and microwaves travel at the speed of light, which is approximately 299,792,458 meters per second (about 186,282 miles per second). This is the maximum speed at which electromagnetic waves, such as X-rays and microwaves, can travel through empty space.
The speed of light in a vacuum is a fundamental constant of nature and is denoted by the symbol "c." It is the same for all forms of electromagnetic radiation, including X-rays, microwaves, visible light, radio waves, and others. No matter what the wavelength or frequency of the electromagnetic wave is, they all travel at the same speed when moving through a vacuum.