"Nobody was more surprised than us when we became pop stars," muses Andy McClusky, co-founder of synth pop pioneers Orchestral Manoeuvres in the Dark, as he looks back on a career spanning German experimental soundwaves to Atomic Kitten.

Twenty five years after OMD released groundbreaking album Architecture and Morality, establishing them as one of the country's most influential electro-pop bands, Andy has reunited with Paul Humphreys.

"We were asked to do a German TV show together last year and thought why not?'," says Andy. "From there we planned a few gigs. I was petrified when the dates were announced - then they started selling out and it turned into a 38-date tour.

"It's the first time we've played together for 18 years."

They start next week with a tour re-visiting Architecture and Morality, followed by a Greatest Hits tour in June. "The two aren't radically different," laughs Andy. "We're playing some not-so-easy-on-the-ear stuff too. We were an experimental band that ended up having hits, so we're re-claiming our heritage! It's the first time we're playing all songs from Architecture and Morality live. Each one has a new film with it."

In the 1970s Andy and Paul were teenagers carrying out strange musical experiments with old radio sets and tape recorders in their bedrooms.

"I got my first synth from my mum's Kay's catalogue, but before that we used to pump everything - war noises off the TV, everything - through tape recorders," says Andy. "Sitting here at my computer, editing new material, those early electronic experiments seem a world away."

It all started the day he discovered Kraftwerk, in 1975. "I sat in seat Q36; it was the first day of the rest of my life. I built a stereo from two old record players and started raiding obscure German back catalogues. Our mates thought our music was awful.

"Actually we were Andy and Paul no-mates - or Andy and Paul don't-want-any-mates," he laughs. "We didn't want anyone interfering."

After naming themselves Orchestral Manoeuvres in the Dark they launched their distinctive style of catchy electronic melodies. Intelligent pop you could sing along to.

As well as Kraftwerk, the pair have Liverpool's late 1970s music scene to thank. Everyone was in a band, between bands or forming a band, and central to it all was Eric's Club, the venue for OMD's debut performance in October 1978.

"OMD wouldn't exist if it wasn't for Eric's," says Andy. "It was full of musicians who went on to form bands like Teardrop Explodes, Echo and The Bunnymen and Frankie Goes To Hollywood. To us they were just a bunch of penniless schmucks!"

One of the appealing things about OMD is their ability to blend melody and melancholia, writing infectiously catchy songs about unlikely subjects like oil refineries, religious icons and silent movie stars. Enola Gay was a dance-pop song inspired by the plane that dropped the atomic bomb on Hiroshima.

Their commercial appeal caught the attention of Factory Records supremo Tony Wilson, who released OMD's first single, frenetic dance classic Electricity, on his label.

"We went to Manchester to blag our way onto Granada Reports," says Andy. "We were shocked when Tony Wilson said we had pop potential. We were going to change the world; we never intended to be commercial. It wasn't deliberate that as well as all our experimental stuff we also wrote songs your granny could whistle at the bus stop. It just happened that way.

"Despite selling three million records we didn't change the world. You're writing songs about Joan of Arc... what do you expect?' was what some music journalists told us."

The ethereal 1981 album Architecture and Morality album was OMD's finest hour. Blending choral effects and wistful melodies, it produced top five singles Souvenir, Joan Of Arc and epic follow-up Maid Of Orleans. OMD became Smash Hits cover stars, singing on Top of the Pops.

Then came 1983 album Dazzle Ships, a commercial flop. Described as a fractured futurist soundscape of ideas drawing on everything from Eastern European radio broadcasts to industrial robots', it was never going to set the charts on fire.

"If we'd stuck to our original formula, or released Architecture and Morality 2, we'd have made more money, but that wasn't what we were about," says Andy. "We were pushing boundaries."

Junk Culture - which produced Tesla Girls, Locomotion and Talking Loud and Clear - proved they could still create classic three-minute pop songs with a lean to the unusual, and American chart success came with You Leave, written for 1986 movie Pretty In Pink. But in 1989 Paul left Andy to continue with a new OMD line-up until the mid-90s.

"I begrudgingly called it a day in 1996. At the height of Britpop nothing was more out of date than an Eighties synth band," says Andy.

Creating a girl group might not seem the most obvious route for someone who started out emulating German experimentalists, but that's exactly what Andy did. He founded Atomic Kitten and wrote their biggest hit, Whole Again, in 2001. It was his only Number One and earned him an Ivor Novello nomination.

"Atomic Kitten exist because of Kraftwerk," he says with a straight face. "Let me explain: when I worked with Kraftwerk I was told to always create a vehicle for my songs and the right vehicle for Whole Again was Atomic Kitten. There's nothing wrong with a good pop band and I believe Atomic Kitten had great potential. I had a blast working with them."

He's back on familiar territory with OMD. The band are working with artist Peter Saville on an audio-visual installation based on electricity-generating power facilities - what else? - and next year they will perform back catalogue songs with the London Philharmonic Orchestra.

"I'm looking forward to touring again," adds Andy. "For a working-class kid from the suburbs of Liverpool, the opportunity to travel which came from being in a band was something I'd never have had otherwise."

OMD are at Sheffield City Hall on June 17. For tickets ring (0114) 2789789. They have recently released a new remastered version of Architecture & Morality.