From Lyon Saint-Exupery airport

There as buses named SATOBUS managed by the company Faure.
The journey lasts 1:05H. Return ticket price : 30euros

Saint-Exupery to Grenoble

Take the bus at the arrival level.
The tickets may be bought in the bus.
There are buses from 7:30am to 9:45pm every hour or less, during the week from Monday to Friday. Less frequent for weekends and holidays. For detailed information, please refer to the website of the bus company.
The final stop is the Grenoble bus station close to the railway and tram station.

Grenoble to Saint-Exupery

Take the bus at the Grenoble bus station close to the railway and tram station. 
Tickets should be bought in the bus station terminal.
There are buses from 5:00am to 7:00pm every hour or less during the week from Monday to Friday, and less frequent for weekends and holidays. Please refer to the website of the bus company for details.
The final stop is at the airport departure level.