Granted there is some research around the benefits of aligning IT with the business but not around quantification of ROI and nothing that I can find specific to ITIL.
The itSMF themselves make a few outrageously unsubstantiated claims in their pocketbook An Introductory Overview of ITIL:
New product cycles reduced by 50%.
Send no money now!!
Before it mysteriously disappeared, the Best Practice Research Unit (BPRU) was a website claiming to be associated with the ITIL v3 Refresh (After twenty years of ITIL, it is high time there was such a unit.)
It is a shame there is no such initiative from either OGC or itSMF (at least itSMF USA is doing something, in fact several things focused on research). The BPRU website explicitly recognised the evidence problem:
"Much of the material published on IT management, including IT service management, has been normative or prescriptive in flavour. Few rigorous, academic studies have been undertaken to evaluate how tools, techniques, methods and management approaches have been selected, adapted, implemented and measurable benefits achieved. There is a danger that new approaches arise out of the practitioner community with little empirical validation."
Few rigorous, academic studies
? Dont be kind. The solitary piece of academic research I can find carries a bold and, I think, unproven title Evidence that use of the ITIL framework is effective . It opens by saying Very little academic material exists on ICT Service Management Best Practice
and concludes its own research with:
"We found that both customer satisfaction and operational performance improve as the activities in the ITIL framework increases. Increased use of the ITIL framework is therefore likely to result in improvements to customer satisfaction and operational performance. Although the study was limited to a single research site, claims made by executive management of the research site and OCG as to the contribution the ITIL framework seems to be justified. More definitive research delineating the nature of these relationships is however needed, especially regarding each process in the ITIL framework."
The database is poor:
research site was a large service unit of ICT in a provincial government in South Africa during 2002/3 one site.
More importantly, the two things measured to support this brave conclusion were (1) customer satisfaction (the three surveys they conducted only included management in the final survey so all we can say is that non-managerial staff were happier) and (2) objective service improvement by measuring the number of calls logged at the Help Desk because we can rather safely conclude that the number of problems logged would be a good reflection of objective service levels."