I have an Espresso machine that is 208v 1 phase, what are the electrical requirements if the outlet is currently 120v?

You need more info than that... a lot more... and no matter what you aren't plugging it into 120 and getting it to work... you need a transformer... how big of a transformer you need depends on the other information you left out about its requirements.

It's best to run a new line because you need a line with two hot and one neutral/ground. If it will not work on 240 volts you will need a step down transformer to get 208 volts, but a 208 volt appliance will work on 220-230 volts without a problem. Check the nameplate first to see what it will take.

It's best to run a new line because you need a line with two hot and one neutral/ground. If it will not work on 240 volts you will need a step down transformer to get 208 volts, but a 208 volt appliance will work on 220-230 volts without a problem. Check the nameplate first to see what it will take.

They have a SINGLE phase device... such as is common outside the USA like In Europe. As such they won't have two hots.

Oh yes they do have two hots. This is a single phase with two hot wires, with three it called a three phase power supply. With two hots you have one waveform between the two hot wires; with three phase you have three waveforms where each one leads the other. Three phase can be Wye or delta. Wye (Y) has all equal voltages and delta has a high leg. When running single-phase equipment you NEVER use the high leg because it's 200+ to ground and tears up equipment through ground faults. It's true you can go from the delta high leg to ground and get 200 volts which will run the equipment, but it won't run for long due to the ground fault problem. Know which one you have before hooking up equipment.