Weyl semi-metals are an exciting new class of 3D materials with exotic transport properties. They are characterised by point like singularities in the Brillouin zone at which conduction and valence bands touch. Around these points the electronic quasi-particle excitations can be described by either left- or right-handed Weyl spinors. This makes high energy physics to be the low energy electronics of these materials. Holographic models might be useful in two ways: first some Weyl semi-metals might be strongly interacting and second holography is our best tool to understand and discover new exotic transport properties related to the chiral nature of the charge carriers, especially to chiral anomalies. I will review the construction of a holographic model supporting a topological quantum phase transition between a topological Weyl semi-metal phase and a trivial phase and use it to predict the existence of a new dissipation less form of viscosity (Hall viscosity) in the quantum critical region.

Chiral anomalies have profound impact on the transport properties of relativistic fluids. They are closely related to the creation of currents by magnetic fields or vortices in the fluid via the so called Chiral Magnetic Conductivity and the Chiral Vortical Conductivity. Both can be computed by Kubo type formulae from special kinematic limits of two point functions of currents. I will review the calculation of these conductivites in a gas of free Weyl fermions and at strong coupling via a holographic model. A special and somewhat mysterious role is played by the mixed gauge-gravitational anomaly.