The effect of the addition of antimony doped tin oxide (ATO) nanoparticles on the electrical conductivity of acrylate films is described. To enable dispersing of ATO in acrylate matrices, 3-methacryloxypropyltrimethoxysilane (MPS) was grafted on the surface of the filler. The amount of MPS used for this surface modification was found to strongly affect the electrical conductivity. Surface modification with a large amount of MPS resulted in colloidally stable dispersions of ATO, leading to a homogeneous distribution. Surface modification with small amounts of MPS led to instable ATO dispersions and aggregation of ATO into a fractal type network, which gives a much higher conductivity especially at low-volume fractions. For composites with a fractal type ATO network a second effect was found. Decreasing the amount of on ATO grafted MPS resulted in an increase of the electrical conduction between the ATO particles.