  We performed a detailed study of the 2007 outburst of the 352s pulsar
SAXJ2103.5+4545, a Be/X-ray transient observed by INTEGRAL, to study its
spectral and temporal properties during the evolution of the outburst.
SAXJ2103.5+4545 was observed with IBIS/ISGRI from 25 to 27 April 2007 and from
6 to 8 May 2007. The 20-100keV spectrum is well described by a bremsstrahlung
model with a temperature kT = 24keV. The pulse profiles are variable with time
and energy. A pulse period derivative of pdot = -3.4E-7 s/s has been observed
during the outburst. Instead, a spin-down of pdot = 5.5E-9 s/s is observed
between the 2007 outburst reported here and the previous one occurred in
December 2004. This is the largest spin-down measured for SAXJ2103.5+4545 since
its discovery. We estimate a neutron star magnetic field in the range
(1.6-3)E13 G using the Ghosh & Lamb torque model.
