Cash return on invested capital (CROIC) is similar to ROIC, except that it looks at cash investment and returns.
This means using cash returns rather than a profit measure for the denominator. The line between CROIC and ROIC is rather blurred as EBITDA is arguably a cash flow measure, and therefore using it gives a CROIC rather than a ROIC.
CROIC may be calculated using one of many cash flow measure such as free cash flow or operating cash flow. Free cash flow has the advantage of being the most most accurate measure of the returns to providers of capital.