The chancellor's CV
Hammond leaves his post as foreign secretary, which he has held for two years. Before entering the Foreign Office, Hammond was responsible for transport, and after, defence, and he had held various shadow cabinet positions before the Conservatives came to power.
What kind of economic policies will Hammond support?
Hammond defended banks in 2012, saying they weren't the only ones responsible for the financial crisis because "they had to lend to someone" and has said that people who took out loans were "consenting adults" who were looking for a scapegoat in the aftermath of the financial crisis.
Speaking to the Daily Telegraph four years ago, Hammond said families had to shoulder their share of the blame for the 2008 financial crisis. He said: “People say to me, 'it was the banks’. I say, 'hang on, the banks had to lend to someone’.
"People feel in a sense that someone else is responsible for the decisions they made. Of course, if banks don’t offer credit, people can’t take it. [But] there were two consenting adults in all these transactions, a borrower and a lender, and they may both have made wrong calls.
"Some people are unwilling to accept responsibility for the consequences of their own choices."
Households were spending more than they earned. That’s why household debt rose.
Hammond may, then, take a harder line than May if she tries to relax Cameron's austerity plans; he also played a key part in creating Cameron's economic policies.
Hammond's big hurdles
The chancellor's biggest challenges will be defending the City's international prowess, securing strong trading relationships for Britain, and making sure investment and employment remains strong while the future of the country is uncertain.
Hammond will need to secure the passporting rights for the City's big banks to keep London as a financial centre.
Before working in politics, Hammond was a director of housebuilding company Castlemead Homes, so he understands the priorities of a sector that is now under threat of stagnation. He will also have to work hard to reverse sharp drops in consumer confidence that have been recorded recently, and encourage people to spend.
Hammond's views on Brexit
Like May, Hammond campaigned for Britain to remain inside the European Union. He will be seen as a steady hand; he has said previously that Brexit could take six years, suggesting he is in no mood to rush negotiations and appreciates diplomacy could be slow.
Speaking in the House of Commons on Tuesday, Hammond said Britain must "tread a careful path".
"The concern is this - if a future treaty between the UK and the EU 27 is deemed to be a mixed competence, it will have to be ratified by 27 national parliaments. I think I am right in saying the shortest time in which this has been done in any EU treaty is just under four years, and that is after taking into account the time it has taken to negotiate," he said.
We have to tread a careful path having any preliminary negotiation but remain on the right side of our international negotiations.
However, Hammond's commitment to the Brexit cause is evident. He told MPs yesterday: "Brexit means Brexit".
As foreign secretary, Hammond has built up relationships with senior officials from all over the world, and he has already been informally exploring options for Britain with other foreign ministers.
He has been "smelling the atmosphere" with his foreign counterparts, the Guardian reported, most recently at a Nato summit in Brussels.