Recent developments in the generation, metrology and potential applications of XUV-attosecond (as) pulses, formed by the coherent superposition of harmonics of an infrared femtosecond (fs) laser pulse, are reviewed. Particular emphasis is given to the recently achieved second-order autocorrelation (AC) measurement of a sub-femtosecond (sub-fs) pulse train. The method is a non-trivial extension in the XUV spectral range of the well-established technique routinely used in ‘fs’ pulse metrology. Besides the direct visualization of a periodic attosecond structure and the quantitative information it supplies, the approach introduces a unique technique for the implementation of XUV-pump XUV-probe type of experimental studies of ultra-fast phenomena. It further relates to the metrology and time domain application interests of other advanced XUV radiation sources, such as the XFEL-based installations. While the implementation of the method and its refined versions with laser harmonics is a challenge at the limits of the realizable, the profoundly high scheduled intensities of XFEL sources are expected to sufficiently enhance its robustness and range of applicability.