  We consider thermal strongly-coupled N=2 SYM theory with fundamental matter
at finite isospin chemical potential. Using gauge/gravity duality, i.e. a probe
of two flavor D7-branes embedded in the AdS black hole background, we find a
critical temperature at which the system undergoes a second order phase
transition. The critical exponent of this transition is one half and coincides
with the result from mean field theory. In the thermodynamically favored phase,
a flavor current acquires a vev and breaks an Abelian symmetry spontaneously.
This new phase shows signatures known from superconductivity, such as an
infinite dc conductivity and a gap in the frequency-dependent conductivity. The
gravity setup allows for an explicit identification of the degrees of freedom
in the dual field theory, as well as for a dual string picture of the
condensation process.
