Abstarct: Study of electrical and magnetic properties of manganites has attracted much interest after discovery of CMR phenomenon. In this work, we investigated electrical transport in manganite thin films and for this purpose we chose thin films of La0.67Ca0.33MnO3 with thicknesses of 4/5, 7, 12 and 37 nm. Temperature behaviour of specific resistivity has been fitted by theoretical models above and below TC. We calculated density of states, localisation length, activation energy, and residual resistivity from the best fitted model to experimental data and then we interpreted the results considering strain and lattice mismatch effects.