Certain classes of experiments would benefit from the availability of x-ray pulses of shorter time duration than what can be achieved today. These include accurate measurements of frequency and those of time resolution. One way to generate short x-ray pulses, is to utilize only part of an originally longer train of photons, and discard the rest. This approach is of little help if the phenomenon under study (such as synchrotron radiation pumped x-ray lasers) requires not only short pulses, but also high instantaneous photon intensity. When the time averaged photon intensity cannot be increased, the required threshold for the instantaneous intensity could nevertheless be reached (and the time resolution improved), if the time duration of individual photon pulses could be reduced without losing significant numbers of photons in the process. The term ‘‘equitemporal optics’’ denotes a collection of optical elements which can bring about a photon pulse length compression of this type. We demonstrate in general that practical equitemporal optics for x rays requires at least one optical element which is nonstationary. It is also shown that an equitemporal optics can be constructed for x rays by making use of only a single rotating mirror, while all other elements are stationary, provided that at least one of the stationary elements is a reflector. Furthermore, that reflector cannot be a single continuous mirror, but must contain more than one appropriately positioned discontinuous section. The number of sections must not be less than the time compression factor, ft, by which the original pulse length is to be reduced. Examples of appropriate reflectors are given. An equitemporal design of this type is presented which utilizes such a reflector together with a mirror rotating with a constant angular velocity. The time compression factor of this device is calculated. It depends, among other things, on the emittance of the photon beam and the mirror speed of rotation. Limiting parameters and conditions will be discussed. Assuming the photon beam emittances produced by the PEP ring in Stanford, in conjunction with mirror speeds which can be achieved in practice, one can show that subpicosecond x-ray photon pulses can be generated in this manner. Alternatively, assuming the projected lower PEP emittances, one expects pulses of only a few femtoseconds duration. Concurrently, the same device will increase the instantaneous x-ray intensity by a factor in the range 102–104. The device may also be utilized to sharpen the leading (or trailing) edge of a photon pulse, without significantly altering the total pulse length.