An effort was made to develop semiconductor oxide-based room temperature dilute magnetic semiconductor (DMS) thin films based on wide band gap and transparent host lattice with transition metal substitution. The Sn1 − xNixO2 (x=0.00,0.03,0.05,0.07,0.10,and0.15) thin film samples were prepared on glass substrates by flash evaporation technique. All the samples were shown single phase crystalline rutile structure of host SnO2 with dominant (110) orientation. The Ni substitution promotes reduction of average crystallite size in SnO2 as evidenced from the reduction of crystallite size from 40 (SnO2) to 20 nm (Sn0.85Ni0.15O2). In the energy dispersive spectra as well as X-ray photoelectron spectra of all the samples show, the chemical compositions are close to stoichiometric with noticeable oxygen deficiency. The crystalline films were formed by coalescence of oval-shaped polycrystalline particles of 100 nm size as evidenced from the electron micrographs. The energy band gap of DMS films decreases from 4 (SnO2) to 3.8 eV (x= 0.05) with increase of Ni content. The magnetic hysteresis loops of all the samples at room temperature show soft ferromagnetic nature except for SnO2 film. The SnO2 films show diamagnetic nature and it converts into ferromagnetic upon substitution of 3 % Sn4 + by Ni2 +. The robust intrinsic ferromagnetism (saturation magnetization, 21 emu/cm3). Further increase of Ni content weakens ferromagnetic strength due to Ni-O antiferromagnetic interactions among the nearest neighbour Ni ions via O2 − ions. The observed magnetic properties were best described by bound magnetic polarons model. © 2016, Springer Science+Business Media New York.