The Proteas were widely criticised for their all-pace attack in the recent World Cup but the pool of 30, which must be whittled down to 15 by August 11, marks the start of a drive to develop slow bowlers for the international stage.
Spinners Gulam Bodi, Johan Botha, JP Duminy, Justin Ontong, Paul Harris and Thandi Tshabalala have all been included after missing out on the one-day squad which reached the World Cup semi-finals in the Caribbean.
McKenzie, who last played for the one-day side in 2003, has been rewarded for his performances in last season's domestic Twenty20 competition when he captained the Johannesburg-based Highveld Lions to victory.
South Africa will open the inaugural world championships when they take on the West Indies at the Wanderers in Johannesburg on September 11.
Probables: Graeme Smith (capt), Hashim Amla, Loots Bosman, Gulam Bodi, Johan Botha, Mark Boucher, AB De Villiers, JP Duminy, Herschelle Gibbs, Andrew Hall, Paul Harris, Justin Kemp, Jacques Kallis, Charl Langeveldt, Neil McKenzie, Albie Morkel, Mornie Morkel, Andre Nel, Makhaya Ntini, Justin Ontong, Alviro Petersen Robin Peterson Vernon Philander, Shaun Pollock, Dale Steyn, Roger Telemachus, Alfonso Thomas, Thandi Tshabalala, Johan van der Wath and Morn van Wyk.