The magnetic ground state of nanocrystalline SrFe0.9Ti0.1O3-delta system has been investigated from 2 K to 300 K using AC Susceptibilty (ACS), magnetization and neutron diffraction measurements. The cusp in the temperature dependent magnetization and dispersion below T-max (the temperature at which the maximum susceptibility is observed) in real part of ac susceptibility with frequency is observed. Arrott plot shows the lack of M-S (spontaneous magnetization) down to 2 K, and the non-occurrence of magnetic Bragg reflections below the T-max in neutron diffraction measurements, indicates the absence of long range ferro and antiferromagnetic order. The frequency dependence of T-max obeys Vogel-Fulcher model establishing the cluster spin glass behavior in this system. (C) 2013 Elsevier Ltd. All rights reserved.