Return on investment (RoI) is similar to ROCE but is a broader term that can be applied to particular projects or operations, whereas as ROCE refers to returns at the company level.
RoI is the profit an investment generates as a proportion of the value of the assets used to generate it:
EBIT ÷ value of assets
RoI obviously needs to be compared to cost of capital, but the cost of capital for a particular project may not be the same as that for a company as a whole. If an investment is in line with a company's business as a whole (in terms of risks to cash flows it will generate) then the company's cost of capital may be used, otherwise it needs to be adjusted.