Andy Pag, of London, and his co-driver John Grimshaw, of Poole in Dorset, would be traveling in a Ford Iveco Cargo lorry powered by fuel that began life as chocolate. The 4,500 mile (7250km) trip across the Sahara should take about three weeks.
The pair will take a small processing unit with them to convert waste oil products into fuel, which they will then donate to an African charity, along with the lorry.
They are taking 2,000 litres (454 gallons) of bio-diesel made from 4,000kg (8,818lb) of chocolate misshapes, the equivalent of 80,000 chocolate bars, to fuel their adventure.
But they will not be able to dip into their tank if they feel peckish as the bio-diesel does not look or smell like chocolate. The fuel is made from cocoa butter, which has been extracted from waste chocolate.
The pair will being their journey by driving through France and Spain and then catch another ferry to Morocco.
Pag, who is 34 and from Croydon, and 39-year-old Mr Grimshaw, an electrician, will then cross the length of the country to Mauritania.
From there they will cross the desert until they reach the city of Timbuktu, in the west African country of Mali.
Both men are keen environmentalists and want to raise awareness of the benefits of bio-diesel, which produces lower carbon emissions than fossil fuels and is made from renewable resources.
Pag, an engineer-turned journalist, has already been to Africa several times but said he wanted to make this trip carbon-neutral.
He approached Ecotec, a firm in north-west England which makes fuel from renewable resources and had been in talks with a large chocolate manufacturer about recycling chocolate into green fuel.
Pag said: "Timbuktu is a city which is being eaten away by the encroaching desert. It's at the sharp end of climate change.
"Timbuktu is renowned as being the back of beyond, the furthest place away that you can possibly imagine and if we can make it there with bio-fuel there's no reason why motorists can't use it on the school run or on their commute to work.
"I have made many expeditions and visited these amazing landscapes but to get there I have contributed to their destruction by driving a guzzling diesel engine.
"I wanted to do something that's carbon neutral. What we have actually done is carbon negative."