The song's riff has a surprising origin. Slash told MusicRadar.com: "It is definitely a metal riff but it was actually inspired by some music I heard when I was in Spain at a hotel. It was the kind of music you'd never have guessed could inspire it in a million years. I got the melody stuff in my head and your brain has a way of turning things around. When I got to the gig that night in the dressing room I turned it into this other thing and that's what Halo is."

Most of Apocalyptic Love was written on the road, whilst Slash and his band was touring. The top-hatted one told MusicRadar: "Musicians that say they can't write on the road are usually busy doing something else! I think it's been my way of keeping myself out of trouble, to take all the energy I used to put into partying and spend it on the guitar. But it's very inspired. It's not like I make myself do it. I get to my room and I've got ideas so I'll work on them, rather than waiting until later."