Is it possible to use DKK in Malmo, Sweden since it's so close to Denmark? If not, the Copenhagen airport should have currency exchange booths, right? Thanks.

No - you need to use the proper currency in each country - or you will end up having useless currency - or having to pay an outrageous rate of exchange to the merchant (to make up for his loss on the rate and his time wasted having to go change the money).

There will be ATMS in the Copenhagen airport - but they will give you only Danish Krone. To get Swedish Krone you need to use an ATM in Sweden - where you will find them everywhere- just as in the US.

Thanks.

How long are you going to be in Malmö? Airport exchange is a very good idea, actually. And I would use the Danish airport exchange as well, because if I recall it's cheaper to do it in CPH.

ATMS in Denmark can give you only Danish currency. You have to use an ATM in Sweden to et Swedish currency.

If you try to change US cash for Swedish Krone in Denmark you will be charged 2 separate sets of fees - one from US$ to Danish Krone and another from Danish to Swedish. (Bureaux de change can only conduct transactions in which one of the currencies is that of the country they're in.)

Ah, I was thinking if you change SEK into DKK at the Danish airport, it is much cheaper than SEK -> DKK at Arlanda, for example.