The influence of thickness on the properties of cadmium oxide thin films deposited using simple and cost-effective chemical spray pyrolysis technique is studied. The maximum film of thickness 2752 nm is achieved by tuning spraying parameters. The thickness dependent structural, morphological, and optoelectronic properties of CdO thin films have been investigated in detail. The microstructure of CdO thin films significantly changed from rough to smooth and further to rougher surface with increase in film thickness. This behavior has been further confirmed from water contact angle measurement. The optical studies show that the direct band gap energy values ranging between 2.23 and 2.46 eV. The Hall effect measurement indicates that all the films exhibit n-type semiconducting behavior with their electrical resistivity lies in the range of 12.8 x 10(-4) to 3.7 x 10(-4) Omega.cm. The CdO film with thickness of 1371 nm exhibited the best optoelectronics properties (transmittance of 74%, figure of merit of 18.23 x 10(-3) (Omega)(-1), carrier concentration of 730 x 10(2) /cm(3) and mobility of 23.11 cm(2)/Vs) among all the films. (C) 2017 Published by Elsevier B.V.