One of the critical blocks in OFDM based transmitter is its power amplifier and the design is aimed for high linearity with maximum power efficiency. This paper describes the design and fabrication of S-band solid state high power amplifier using GaAs power MESFET device for OFDM transmitters. The amplifier operates at center frequency of 2.3 GHz with a bandwidth of 200 MHz. The typical output power is 40 dBm (10 Watt) with 12.5 dB gain. O1P3 of 52.5 dBm indicates the high linearity of this amplifier with power efficiency of 38 percent. The design is simulated using ADS 2002 C and results are measured using Agilent E4407B ESA-E Series Spectrum Analyzer, Agilent E8363B PNA and, HP E8257D RF signal generators.