Oslo to Malmo

I looked up that route on http://www.sj.se. It looks like you need to go via Stockholm: Leave Oslo at 16:56, arrive in Stockholm at 21:50, leave Stockholm at 23:14, arrive in Malmo at 06:48.

That's a nearly 14-hour trip by a pretty indirect route. You can do it much faster and more directly (traveling via Goteborg, for example) if you take daytime trains.

It appears there is no true night train ( direct). You will have 2-4 train changes through the night; one option I saw has you sitting in a station for 3 1/2 hours in the middle of the night. Not exactly a relaxing trip.

You could take an overnight ferry from Oslo to Copenhagen and travel to Malmo from there. Here is one option:

http://www.dfdsseaways.co.uk/ferry-routes/other-routes/ferries-to-denmark-norway

For what its worth flying to CHP seems to b e the best suggestion:

http://www.rome2rio.com/s/Oslo/Malm%C3%B6

Train Oslo 23min - every 15 minutes $11 - $15
Fly Oslo (OSL) 1hrs 10min $40 - $100
Train Copenhagen (CPH) 19min - every 15 minutes $7 - $14
Malmö

Train Oslo S 45min - every 30 minutes $12 - $17
Bus Moss stasjon 3min - every 5 minutes - line 580 $5
Train Mosseporten Senter 1hrs 50min - once a week - line 303 $17 - $24
Train Göteborg Central 2hrs 31min - every 3 hours $35 - $95
Malmö Central

Bus Oslo Bussterminal 3hrs 29min - hourly $20 - $50
Train Göteborg Central 3hrs 16min - hourly $35 - $95
Train Malmö Triangeln station

There has not been an overnight train on that route for a couple of years. I'm guessing that Copenhagen might be your actual destination, anyway. Options are correctly laid out above for day train, overnight ferry, or flight.

Or you can drive. We did that once when our flight back to Copenhagen was cancelled by an ATC strike. The drop fee was horrendous, however!

We have friends with a summer home on the water a bit south of Oslo. I loved sitting on their porch watching the ferry to or from Copenhagen float by. Seems like it would be a lovely journey, even at night ( since daylight lasts so late). I have heard it can be quite a party scene on weekends, however.