While in Nairobi I might need to top up my supply of USD. Is it possible to get it directly from an ATM or will I need to go to a currency exchange?
Yes, I have successfully withdrawn USD from KCB in Nairobi a couple of times. Here is the location I have done this: http://goo.gl/maps/fvojb
There is rumor that there is at least one ATM with an USD cash option:
I found one KCB ATM (across from main post office in Nairobi) which gives you the choice to withdraw in KSH or US dollars.
Source: Lonely Planet
Drop a line here if you could confirm it!
There is a USD atm at the KCB Kipandi House (across the road from the post office) but when I went there on 2/8/15 it was out of order. It is the one on a the far right as you enter (ones with USD are not labelled). I cannot confirm the one at Anniversary towers as I went there on a Sunday and could not get access to the ATMS. I was told by locals there we one at kencom. I could not see one providing USD when I went there. I only checked the atms on the northern side though. There may still be something there as it is the main office for KCB.
I ended up being able to get 1000 USD from the KCB atm at Karen Shopping centre. It is the one on the right. This is the closes atm for all those starting overland tours from Karen Camp. I heard that other people could only get 300 USD from this one so it may depend on your own bank.
Also the KCB at Moyale does not give USD
Yeah! Nowadays it is possible to withdrawal dollars in Kenya ATMs, You can get these services from I&M bank at Gigiri near WarWick building, several KCB ATMS such as two in Kencom but you need to ask the soldier there to show you, 1 in Kipande house, 1 in Sarit Centre, 3 ATMS in the JKIA and 1 in TRM.
Though it seems every answer is equally valid they might benefit from some organisation:
Date User Where Notes 20121019 Dan KCB across from main post office 20121115 shnozolla KCB US local bank card 20130416 user6326 KCB Village Market near UN Headquarters up to 300 USD 20141128 mark the mall withdrawn US $1000 20150603 Danny KCB Univerity way Anniversary towers 1 machine KCB Kipande House 1 machine KCB Kencom 2 machines 20150808 Bradley KCB Karen Shopping centre Gibbs 20160302 Mark TRM 2nd flour 20160901 Lawrence I&M bank Gigiri near WarWick building Kimani KCB Sarit Centre JKIA 3 ATMS TRM 1 20170209 Kelvin KCB and Banklays Bank also UERO Jackson