Nairobi is 1 hour ahead of Madrid
Best overlap: 8:00 AM to 5:00 PM in Madrid is 9:00 AM to 6:00 PM in Nairobi.
For the smoothest call, aim inside 8:00 AM to 5:00 PM in Madrid, i.e. 9:00 AM to 6:00 PM in Nairobi. Nairobi is 1 hour ahead of Madrid, but you'd hardly notice — 9 hours of shared hours makes this feel like working in neighbouring time zones. Don't be caught out by clock changes — Madrid observes daylight saving and Nairobi doesn't, so the offset varies by an hour through the year.