The cognitive radio is an opportunistic scheme for accessing unused spectral bands by unlicensed users. This allows unlicensed users to transmit data over licensed band not used by the primary user and increases spectral efficiency by utilizing the vacant frequency slots. The lack of central management restricts the ad hoc cognitive users to efficiently access the unlicensed channels. In this paper, we discuss methods for spectrum access to unlicensed users for the benefit of the entire network. We incorporate game theoretic techniques to overcome the short-coming of underutilized spectrum and maximize the payoffs of licensed/cognitive users. The spectrum allocation problem in cognitive radios is modeled as a potential game and we observe the behavior of ad hoc cognitive radio networks. The choice of player's strategy is contingent upon the composition of the potential function.