The CIO, more often than not, reports to the CFO and not the CEO. This relationship is unique, in that the CIO needs to understand how the CFO sees the world, and that's a very different view than what the CIO is used to! This blog post by Dr. Jim Anderson starts with what the CFO may not understand:
The first thing that you need to understand is that your CFO is going to be looking for a trusted advisor when it comes to all things IT. The CFO still has their financial responsibilities on top of their new IT responsibilities. What they need is someone to basically tell them what they need to do in terms of IT work. If you play your cards right, then this person could be you. A CFO's worldview generally comes down to trying to understand the ROI associated with every dollar that the company spends. What you need to do as a CIO is to help them to understand that when it comes to IT, this view may no longer be correct. In IT we do a lot of experiments and we have a habit of piloting new projects. It's entirely possible that these activities, as important as they are, may not have a positive ROI. It's your job to make sure that the CFO understands this.
He then goes on to explain what the CFO needs to understand, including how IT expenses might not necessarily look the same as expenses from other departments. The CFO can help here, as they can perform forecasting for the company and help the CIO go forward with only the projects that have the possibility of long term success. This is also a danger, however, as the CIO will have to make sure that the CFO understands that not all IT projects can be thought of in terms of money made. The CIO needs to learn how to communicate effectively with another executive who is, essentially, non-IT. It's going to require some intelligent communication to help the CFO more accurately oversee the operation of IT in a way that helps both the CIO and the organization.