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We present a study of the accretion flow to the intermittent accretingmillisecond pulsar, HETE J1900.1-2455, based on observations performedsimultaneously by XMM-Newton and RXTE. The 0.33-50 keV spectrum is described bythe sum of a hard Comptonized component originated in an optically thin{\tau}~1 corona, a soft kTin~0.2 keV component interpreted as accretion discemission, and of disc reflection of the hard component. Two emission featuresare detected at energies of 0.98(1) and 6.58(7) keV, respectively. The latteris identified as K{\alpha} transition of Fe XXIII-XXV. A simultaneous detectionin EPIC-pn, EPIC-MOS2, and RGS spectra favours an astrophysical origin also forthe former, which has an energy compatible with Fe-L{\alpha} and helium-likeNe-K{\alpha} transitions. Broadness of the two features suggests a commonorigin, resulting from reflection in an accretion disc with inclination of(30+4{\deg}), and extending down to Rin=25(+16,-11) gravitational radii fromthe compact object. However, the strength of the feature at lower energymeasured by EPIC-pn cannot be entirely reconciled with the amplitude of the FeK{\alpha} line, hampering the possibility of describing it in terms of abroad-band reflection model, and preventing a firm identification. Pulsationsat the 377.3 Hz spin frequency could not be detected, with an upper limit of0.4% at 3-{\sigma} c.l. on the fractional amplitude. We interpret the innerdisc radius estimated from spectral modelling and the lack of significantdetection of coherent X-ray pulsations as an indication of a disc accretionflow truncated by some mechanism connected to the overall evolution of theaccretion disc, rather than by the neutron star magnetic field. This iscompatible with the extremely close similarity of spectral and temporalproperties of this source with respect to other, non pulsing atoll sources inthe hard state.

The accretion flow to the intermittent accreting ms pulsar, HETE J1900.1-2455, as observed by XMM-Newton and RXTE