This paper describes the design of printed slot antennas for multi-band applications. The aim of this design is to develop a single antenna that can be used by all the IEEE 802.11 WLAN network standards collectively known as Wi-Fi. It is required to have a polarisation complementary to that of multi-band printed monopole antennas, to achieve polarisation diversity. Design of a printed slot antenna element operating in the 2.4 and 5 GHz bands is discussed. Parametric studies are presented and different types of feedline configurations are investigated. The theoretical results are promising.