I hope that following information will be helpful.

https://www.sciencedirect.com/science/article/pii/S0360319915313069

It is only working temperature in high temperature working you can joint it to gas turbine cycle,... like SOFC.

Differences are:

- operating temperatures HT-PEM: 140 - 200 °C

- no gas humidification required, dry gases can be used.

- electrolyte in HT-PEM is phosphoric acid.

- membrane is PBI or pyridine based instead of Nafion.

- Degradation issues are therefore in several aspects also different compared to LT-PEM.

and more....

I suggest to search the literature.