In this paper, a novel real-valued orthogonal frequency-division multiplexing (OFDM) modulator/demodulator based on discrete Hartley transform (DHT) is presented and implemented for the application in IEEE 802.11a/g wireless LAN. The proposed DHT-based architecture employs two real-valued fast DHT (FHT) kernel instead of the conventional complex-valued fast Fourier transform (FFT) for OFDM systems. By taking advantage of the real-valued operation of FHT, this approach can reduce the number of multiplications compared with the radix-2 FFT. Moreover, the DCT-based radix-2 FHT algorithm is realized to reduce the multiplications of conventional radix-2 FHT. The proposed real-valued DHT-based modulator/demodulator has been designed and fabricated in a 0.18-μm CMOS technology with a core area of 928x935 μm2. The average power consumption is about 20.16 mW at 20MHz and 1.8 V supply voltage.