Senior Office Coordinator

Sublime is advancing a breakthrough, clean, efficient, low-waste process for manufacturing cement, the essential ingredient in the most-consumed human-made material on Earth: concrete. Replacing 200-year-old manufacturing methods that are reliant on kilns running hotter than lava, our near-ambient-temperature, electrochemical technology manufactures industry-accepted cement and critical minerals. We’re partnering with leading general contractors, concrete producers, developers, and technology hyperscalers to deploy our clean, durable, beautiful Sublime Cement® in infrastructure that is defining the future of clean construction. Backed by some of the world’s largest cement producers, leading private investors, and the U.S. Department of Energy, we are assembling a talented, collaborative team that is "amped about cement" (pun intended) and committed to operating on the frontiers of material science, manufacturing, industry, construction, and commercial partnerships, to advance cement innovation that will endure for the next millennium.

Sublime Systems is seeking an organized, resourceful, and proactive Sr. Office Coordinator to support the daily operations of our fast-growing headquarters and help cultivate a high-functioning, mission-driven workplace. This role is ideal for someone who thrives in a fast-paced environment, takes initiative, and enjoys supporting teams through thoughtful coordination and behind-the-scenes execution.

As a key member of the Operations team, the Sr. Office Coordinator acts as a central point of support across teams—managing internal logistics, office facilities coordination, and employee experience. From meeting prep and office upkeep to onboarding support and event logistics, you’ll play a critical role in ensuring our work environment is professional, efficient, and welcoming. The ideal candidate is a hands-on problem-solver who manages competing priorities with poise, anticipates team needs, and takes pride in enabling others to do their best work.

This is a full-time, in-person position in Somerville, MA, with flexibility to occasionally work from home depending on team and project needs.

• Maintain a clean, well-organized, and professional office environment across all shared spaces (desk spaces, conference rooms, phone booths, lounge space, kitchen, etc.)
• Manage office supply and inventory management—track usage, coordinate with vendors, and restock supplies
• Coordinate mail and courier needs, including processing confidential or time-sensitive deliveries
• Coordinate office resource setup and access for new hires and internal moves
• Support ongoing workspace planning and space reconfigurations in collaboration with the Operations and Facilities teams
• Assist with basic IT coordination in partnership with the external IT vendor (e.g., conference room tech, printer troubleshooting)
• Coordinate meeting logistics for internal and external gatherings, including booking rooms, AV setup, and video conferencing tools
• Provide general administrative and event execution support to the Operations team and other departments as needed
• Assist with routing, tracking, and organizing legal and operational documents (i.e. NDAs, patent documents)Assist in developing and maintaining internal directories, operational policies, SOPs, and onboarding materials
• Support planning and execution of team events, social gatherings, and birthday or milestone celebrations
• Serve as a friendly and approachable point of contact for visitors and new hires; direct the team to correct resources for office, IT, and miscellaneous questions
• Proactively identify and suggest improvements to enhance the employee experience within the office

• 3-5 years of relevant experience in administrative, office management, or operations role
• Demonstrated ability to manage competing deadlines and adapt to evolving priorities
• Excellent written and verbal communication skills; professional and friendly demeanor
• Highly organized, detail-oriented, and dependable, with strong follow-through
• Strong proficiency in Microsoft 365 (Outlook, Word, PowerPoint, Excel), Zoom, and calendar management tools
• Comfortable operating with minimal oversight, taking initiative, and navigating ambiguity in a dynamic, fast-paced environment
• Discretion and professionalism when handling confidential or sensitive information
• Can-do attitude & an eagerness to learn

• Prior experience working in a startup, cleantech, or mission-driven organization
• Familiarity with office planning, basic IT troubleshooting, and vendor coordination
• Entrepreneurial and unafraid to tackle complex problems with imperfect information
• Experience supporting executives or high-visibility projects
• Strong interpersonal skills and ability to build trust with colleagues across all levels

Sublime Systems is proud to be an Equal Opportunity Employer

All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, national origin, disability, protected veteran status, or any other characteristic protected by law.

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In compliance with federal law, all persons hired will be required to verify identity and eligibility to work in the United States and to complete the required employment eligibility verification document form upon hire.

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Sublime Systems use E-Verify to confirm the identity and employment eligibility of all new hires.