In line with expectations, first-quarter orders were down from last year's record high, but only by 5 per cent (down 4 per cent on a comparable basis). Overall, we are seeing continued strong customer demand in the project and systems areas, and I am very pleased with the positive development of short cycle business orders in the Electrical Division. So while ABB's order book fell in the first quarter, I am more confident about 2024 than I was at the beginning of the year.
Key results for the first quarter of 2024 include: orders of $9 billion, which exceeded expectations; The book-to-shipment ratio was 1.14, showing a positive trend; Record operating EBIT margin; Free cash flow was $551 million, with strong first-quarter deliveries. We publish our annual sustainability report, one of which focuses on reducing greenhouse gas emissions, a core part of our customer value proposition. In 2023, ABB will help customers avoid 74 million tons of greenhouse gas emissions over the lifetime of products sold. To date, we have helped our customers reduce their emissions by 139 million tonnes, and on this basis, we are on track to reduce our customers' emissions by 600 million tonnes of CO2 equivalent over the life cycle of products sold by 2022-2030.
In line with expectations, first-quarter orders were down from last year's record high, but only by 5 per cent (down 4 per cent on a comparable basis). Overall, we are seeing continued strong customer demand in the project and systems areas, and I am very pleased with the positive development of short cycle business orders in the Electrical Division. So while ABB's order book fell in the first quarter, I am more confident about 2024 than I was at the beginning of the year.
Both the Electrical Division and the Motion Control Division recorded impressive new order volumes. While the order book for the Process Automation division has fallen from its all-time high, it remains consistent with the strong performance of recent quarters. At the beginning of the year, we predicted that the fourth quarter of last year would be a low point for order levels in the Robotics and Discrete Automation division, and that proved to be the case. In the first quarter, the order volume of the division achieved sequential growth as scheduled; However, as customers' order patterns returned to normal after the pre-order period, there was still a significant decline in order volumes compared to the same period last year.
Sales revenue remained stable in the first quarter (+ 2% on a like-for-like basis), supported by both price and volume. I am pleased to see gross margin improve by 270 basis points to 37.3%, a positive change driven by all business units. Efficient management of higher volumes and prices improved the operating EBITDA margin by 160 basis points to an all-time high of 17.9%. I see this as a positive sign that ABB still has significant growth potential and that we can deliver further growth over the medium term within the new margin target announced last November."
The strong cash flow performance at the start of the year has laid a solid foundation for us to achieve good full-year free cash flow again this year, which is expected to be at least in line with last year. The use of cash acquisitions to expand technology and business footprint is an important way to create long-term shareholder value. We are pleased to see the recent acquisition of SEAM, which will add asset management consulting capabilities to ABB's Electrical Services business unit to further meet the needs of the industrial and commercial building markets. We have a portfolio of quality potential acquisition targets, including some larger than recently announced deals. The share repurchase program is an effective tool for us to distribute our remaining cash, and we have announced another annual repurchase program of up to $1 billion, which was officially launched on April 1. While the size of the repurchase program is comparable to last year, the execution period is shorter and will close at the end of January 2025 in order to align with the release of the fourth quarter 2024 results and dividend proposal.
During the quarter, we announced my upcoming retirement as CEO of ABB Group. I will still do my best until the end of July when Marten takes over. After that, until the end of this year, I will serve as a consultant to assist him in the transition period. I am delighted to see Marten take on this challenge and am confident in his leadership skills to further integrate the ABB Way operating model into the way we work." We are deeply saddened to see Mehta leave ABB. He has made an outstanding contribution to the success of the company and I wish him all the best in his new journey. ABB is currently searching for new leaders for its Electrical and Motion Control divisions and believes that Maaten will have a complete and strong management team when he takes over in August.
