In this paper, an algorithm to solve the profit based unit commitment problem under deregulated environment has been proposed to determine the optimal generation schedule with maximum profit. Deregulation in power sector increases the efficiency of electricity production and distribution, offer lower prices, higher quality, a secure and a more reliable product. The proposed algorithm is developed from the view point of a generation company wishing to maximize a profit as a participant in the deregulated power and reserve markets. Unit commitment (UC) is an optimization problem of determining the schedule of generating units within a power system with a number of constraints. Unit commitment schedule depends on the market price in the deregulated market. More number of units are committed when the market price is higher. When more number of generating units are brought online more power is generated and participated in the deregulated market to get maximum profit. This paper presents a new approach of GENCOs profit based unit commitment in a day ahead competitive electricity markets. Generations, spinning reserve, non spinning reserve and system constraints are considered in the proposed formulation. The proposed approach has been tested on IEEE-30 bus system with 6 generating units as an individual GENCO. The results obtained are quite encouraging and useful in deregulated market. The algorithm and simulation are carried out using Matlab software.