In this talk, a brief introduction to string cosmology is given in the begi
nning. We recall duality symmetries and the main ingredients of pre-big ban
g scenario in the context of string theory. One of the interesting aspects
of stringy T-duality symmetry is the possibility of generating new cosmolog
ical solution starting from a known solution of the string effective action
. In the later part of the talk, we apply the soliton transformation techni
que, in the string cosmological context, to obtain new background solutions
. These backgrounds satisfy the equations of motion by construction.